Spraying carb cleaner in '89 TB = interesting response

[rickoregon]

Oh, I forgot to add -- I've ordered a vacuum gauge, as I didn't have that in my tool bag. I'll check the vacuum, as well. Thanks!

 

[xjbubba]

With regard to grounding the "D" terminal of the TPS, as I recall, sensor ground for MAP & TPS are not the same as engine ground; I would'nt "ground" those sensors. I beleive the ECM uses an internal power supply that uses a "return" (a dedicated ground) for the MAP, TPS, and ??? sensors.

 

[rickoregon]

As MAP suggested I started the engine and let it run a very long time - about and hour or two. Every now and then I checked throttle performance, and each time I checked it the behavior was the same - cough, sputter, backfire when attempting to open throttle, and it really backfired if I opened it more than about 1/3... Still winds up strong, though, when I spray in carb cleaner.. hmmm... maybe I should just fill the tank up with carb cleaner from now on! LOL

Anyway, after reading your post, xjbubba, I'm going to hold off on direct grounding the TPS or the MAP sensors until I've exhausted most other approaches.

After reading old_man's post about the 1 V difference between readings with and without TPS direct ground (4.65 using D terminal internal ground and 5.65 using intake manifold as ground), I'm concerned that may represent part of the problem. According the the book, the supply voltage should be about 5V.

I borrowed a Snap-On MT2500-2900 scanner from a mechanic in town, and I'll report the data later... maybe someone here will be able to give me an interpretation based on those additional results. Much obliged, Rick

 

[rickoregon]

Using a Snap-On 2500-2900 Scanner with Jeep-1 adapter I gathered the following live data with the engine warm.. I'm presenting the readouts separated by a slash. First value is at idle and the second is at 2300 (once I got engine up to speed with a few shots of carb cleaner in the TB).

---------------------------------
RPM: 630/2300 O2(V): 1.8 - 4.9 / 0.43*; INJ (mS) 4.7 / 4.7
Loop Stat: open/open**; Exhaust: lean/lean
ST Fuel Trim: 128/128; LT Fuel Trim: 128/128
MAP Sensor (V): 1.6/0.9; MAP (kPa): 41/28
Man Vac (kPa): 54/61; Baro Press (kPa): 94/89
TPS (V): 0.74/0.98; Throttle (%): 15/20
Throttle Sw: CLSD/Partial; Fuel sync: + and - intermittent / same
Coolant (C): 104/104; Charge temp (C): 78/73
Spark Adv (BTC): 14/32; Knock: 0/20-30
A/C switch: off/off; A/C request: No/No
EGR: off/off; Bat (V): 13.9/14

--------------
* Note: O2 reading after returning to idle from a carb-induced 2300 rpm would stay low for a bit, then start climbing again back to 3 to 4V. I disconnected the O2 sensor at one point and that did not change performance -- scanner showed a constant 4.98V then.

** The loop status never showed closed. Showed open all the time, except when I backed off the throttle from 2300 after test, then it showed decel briefly.

Has anyone else used a 2500 scanner on their Renix systems? Does anyone know how to interpret these results? This is the first time I've used a scanner, so I'm not sure what the bottom line is from this data.

Also, why does the scanner show open loop status, even though the engine is clearly warmed up? Bad ECM, perhaps? Bad coolant temperature sensor?

And why does the O2 sensor indicate lean, when it's clear from examining all the plugs that engine is running rich?

Thank you for any additional help you can provide. Rick

 

[xjbubba]

Not too fmiliar with the Jeep ECM, but beleive the operating scheems are similar to the GM ECM. So, i'll address your observations given my knowledge of the Chevy stuff. First, O2 and open loop operation. Generally the ECM would look at coolant temp (>~160*F--your ~220*f),time (generally >1 min), and an O2 signal to the ECM that is constently varying between .1v and .9v. Here's where I see a problem or a significant difference between Jeep and Chevy--you see 1.8 to 4.9 volts at idle and .43v at 2300rpm? And with the O2 sensor disconnected, you see 4.89v? Can you confirm these readings are volts, and not milivolts? Your O2 sensor should be a voltage generator that reacts to varying oxygen levels in your exhaust. If it's a "normal" O2 sensor (like most vehickles), it will output very little voltage with a lean mixture (lots of oxygen) and up to 1 volt with a very rich mixture. In closed- loop, the ECM tries to keep the mixture mooving above and below the lean/rich point, which for Chevy is above and below ~.450v. The rapid change above and below the .450v point is called "cross-counts"; besides temp and time, the ECM needs sufficient cross-counts to go into closed-loop. Maybe some one else has put a DVM or scanner on there Early Jeep ECM and can confirm your numbers. I did a long time ago, but can't remember what I saw, but as I recall it was similar to my Chevy ECM. So as far as the O2 goes, i'd verify the numbers and possibly check continuity between pin "C" of the sensor to pin "D9" of the ECM; the other two pins on the O2 sensor connector are for the O2 heater--pin "A" to 12v and pin "B" to engine ground.
Next is your MAP readings. You show 1.6v at idle and .9 at 2300rpm. Normal for idle (hot) is ".5 to 1.5V", increasing to ~4.8v at wide open throttle; MAP voltage should increase as RPM/load increases. Best way to test is with a vacuum pump and a DVM. But you should connect a DVM to pin "B" of the MAP connector. Check for "4 to 5 volts" with key on and engine off; Your scanner will probably work as well. You can also check for continuity between MAP connector pin "B" and ECM pin "C6".
Let us know what you determine.

 

[rickoregon]

...you see 1.8 to 4.9 volts at idle and .43v at 2300rpm? And with the O2 sensor disconnected, you see 4.89v? Can you confirm these readings are volts, and not milivolts?

... Next is your MAP readings. You show 1.6v at idle and .9 at 2300rpm. Normal for idle (hot) is ".5 to 1.5V", increasing to ~4.8v at wide open throttle; MAP voltage should increase as RPM/load increases. Best way to test is with a vacuum pump and a DVM. But you should connect a DVM to pin "B" of the MAP connector. Check for "4 to 5 volts" with key on and engine off ...

xjbubba - I returned the scanner, but just got off the phone with the mechanic who loaned it to me over the weekend. He said that most times those O2 readings are in mV, so perhaps I made a mistake, although I tried to get the units right when I wrote them down. I'll do the checks on the O2 and MAP you suggested using my volt/ohmmeter and let you know the results. Thanks again.

 

[rickoregon]

xjbubba, today I performed the tests you suggested as well as a few others described in the Renix fuel injection manual. Here are the results - used volt/ohm meter to perform measurements this time:

O2 sensor and circuit:
-resistance terminals A and B = 11 ohms (FSM spec: 5 to 7)

O2 harness unplugged:
-term C to ECM term D9 = 5 ohm, then 1 ohm after cleaning O2 sensor
harness plug. 1 ohm is same reading I get for wire run from plug to
ECM, so I'm calling it continuity.. (within specs)

-key on voltage between term A and B (or ground to TB): 12.4V, then
0.45V after a couple seconds (within specs, note: units are *volts*
not millivolts)

-key on voltage between C and B: 4.95V (within specs)

MAP sensor circuit (key on, MAP sensor plugged in):
-voltages:
term B and ground: 4.1V (ok per specs)
ECM term C6 and grnd: 4.1V (ok)
C and grnd: 5.0V (ok)
ECM C-14 and grnd: 5.0V (ok)
D3 to grnd: 0V (ok)
-resistances:
term A and D3: 0 ohms (ok)
D3 and B11: 0 ohms (ok)
B and C6: 0 ohms (ok)

MAP run test (hot, MAP plugged in):
-term B and ground: 1.4 - 1.6V, decreasing to 0.8 to 1.1 when throttle open
slightly
-term C and ground: 4.8V

So, what do you think?

I got the new O2 sensor in the mail today, so I might try that, as the O2 sensor is slightly out of spec..

Also, got a new CPS, but I want to hold off on that until I'm sure it's nothing else, because it's a pain to replace..

I might try switching out the injectors, even though I don't have the new o-rings, yet... even, if they leak a bit, I can tell if that's it before the engine gets hot enough to cause a fire.. I hope!

Any more ideas, things to try, would be appreciated. Thanks, Rick

 

[xjbubba]

Looked at your numbers. Can't say much about your O2 output, my Jeep FSM for my '88 4.0L does not give expected voltages for O2 output, but does give heater crkt voltages; yours look good. Not sure about the heater voltage droping off after 2 secs--probably has to do with the engine not cranking. The ECM controls the heater relay based on MAP and engine speed. Only uses O2 heater at idle and during warm-up. My experience with a bad O2 sensor is poor gas mileage and/or inability to go into closed-loop operation; no noticeable drivability problem.
Your MAP readings are inconclusive. They look OK accept for the output whith the engine running. You said the output at Pin-B droped slightly when you "slightly" increased throttle. You need to agressively increase throttle to test the MAP. Your engine-off key-on gives you the expected max output (4.1v in your case) when the engine is under heavy load or wide open throttle. As you increse RPMs you should see a drop in engine vacuum. As vacuum drops, the MAP output at "B" should go up towards 4.1v. Conversely, with key on and engine off, if you apply a vacuum (hand operated pump) to the MAP the voltage should drop lineraly from 4.1 to ~1.4v with an increaes in vacuum to the level you normally have at idle.
Preveously, you said your scanner indicated .9v at 2300 rpm.That would indicate a MAP crkt problem--put a "T" in the vacuum line running from the throttle body to the MAP and check vacuum. Compare vacuum readings with MAP output voltage, as discussed above. My vacuum line from the throttle body to the MAP sensor melted once, causing hard start, bucking and otherwise awlful running, so insure this line is good, and not leaking or restricted in any way.
I'd insure the MAP "system" is correct before changing other components.
You preveously said the Short term trim (ST) was at 128 and Long term trim (LT) was at 128. If your ECM is in open loop, ST is dissabled and will be fixed at 128. If your fuel mixture had been correct prior to the test run, you'd see LT of 128+/-6. But if your ECM is similar to a GM ECM, and you've removed power from the ECM before the test run, the LT would have been reset to 128, so the number would not be indicative of preveous fuel ratio. When running in closed loop the ST adjusts for correct fuel mixture based on O2 input. If it has to significantly adjust the mixture;ie ST significantly different than 128, the LT fuel trim will be adjusted up or down to "remember" the necessary correction; no adjustments take place in open loop.
Anyway, insure your MAP system is OK before proceeding.
I hope my ramblings are of use. Good luck.

 

[rickoregon]

Thanks for taking the time to interpret the data for me, xjbubba - that really helps.

I've ordered a new MAP sensor and some other sensors, as well.

But I've noticed in removing the fuel rail today that the number 3 injector port on the intake manifold is highly corroded... must have happened before I removed the engine, when the car was stored in our barn for a couple years, and rodents built a nest over that area. Probably the urine accellerated the corrosion precess. Anyway, I'm concerned about using the same manifold, so I'm going to transplant the entire intake/exhaust manifold with fuel rail and throttle body assembly from the original '89 engine over to this '87 engine. First need to order a gasket, of course. Still haven't located an online source for the fuel line connector kits (need three), so I may have to call up the Jeep dealer.. darn. And I'd sure like to find an inexpensive online source for the BG-44K cleaner that old_man and other members use.

At any rate I'm definitely enjoying this project. Really getting thrown into the frying pan to learn about the mechanical aspects of a Jeep. So far, I'm impressed with the sturdy construction. And the level of forum expertise and support is excellent.

If anyone has some tips/precautions they'd like to share about swapping manifolds, please post.

Thanks, Rick

--
Rick & Kate Johnson
Venice Ranch, Burns, Oregon 97720
http://home.centurytel.net/venice/

 

[MAP]

Rick,
How many of your spark plugs were fouled?

Were all 6 coated with carbon deposits from too much fuel? Or did some not have much?

I was thinking, if you do have a lean condition, maybe one of your injectors isn't injecting...

I would suggest you check the condition of all the injector connector connections. You might be able to try some contact cleaner on the connector pins of both the injector and harness connector. I would then rinse with alcohol and let air dry. You can then coat the pins with dielectric grease.

If one of the injectors isn't injecting, I don't believe the ECU would know. The fact that the data you obtained says the engine is running lean support this. To compensate, the ECU is probably allowing the other injectors to stay open longer... providing more fuel and compensating for the injector that may not be working correctly.
If you were to remove the spark plugs and all but one or two injectors aren't fouled with carbon deposits, I would say that those injectors are your problem. Just throwing out ideas.

MAP

 

[Tom R.]

If anyone has some tips/precautions they'd like to share about swapping manifolds, please post.

Spray all bolts with PB Plaster several times prior to beginning the task...especially on the exhaust down pipe.

Disconnect battery

Remove gas cap and depressurize fuel system at the fuel rail port. Be sure to have rags to catch fuel.

Remove the air box and unbolt the steering pump, but don't remove the pump lines. Just set the pump off to the side where the air box used to be. Ensure it's upright so you don't dump steering fluid everywhere.

Disconnect the exhaust down pipe (do this step whenever...just as long as it's before you yank the exh. manifold out)

Remove vacuum lines, throttle cable, etc from top of valve cover & bracket.

The books say to remove all of the injectors. Don't do this unless you need to replace them or the O-rings. Just remove the fuel lines from the fuel rail via the quick disconnects. This way, when you have everything disconnected you can just remove the intake manifold with the fuel rail and throttle body still attached.

*****IMPORTANT*****
Be sure to purchase the quick disconnects for the fuel lines before beginning the job. Last time I checked they were a dealer-only item.

You'll need to remove the EGR items after loosening all of the manifold bolts. The two fuel line quick disconnects for HO motors are different sizes, but I don't know about the non-HO motors. I think they are the same.

*****IMPORTANT*****
I highly recommend you use the OEM gasket. Some folks have had good luck with a Felpro gasket. I will only use OEM after the first aftermarket gasket I used blew out after only two weeks. It has reinforcements around the ports. Be sure you get the right gasket...they're different for the earlier motors than the HO motors.

Have some means of cleaning the intake manifold as it will most likely be full of gunk inside.

Check the condition of the motor mounts...it's a good time to replace them if they're bad or very old. The rest of the removal is pretty much self-explanatory. The intake and exhaust manifolds share the same gasket and mounting bolts/studs.

Installation is reverse. Be careful when tightening the manifold bolts & nuts for the studs. I don't remember the torque value, but it's not very much. Also, be sure to torque the bolts in the proper pattern to ensure both manifolds seat correctly. Fixing a stud that's broken off in the head is no fun. :laugh3:

*****IMPORTANT*****
The fuel line quick disconnects need some kind of oil/lube on the O-rings BEFORE you install them. Otherwise, the O-rings are very susceptible to tearing as they are inserted back into the fuel lines.

The high strength steel pipe (part of EGR system) that connects between the exhaust downpipe and intake manifold can be a bear to reinstate. YMMV. Just remember not to force it too hard when threading back into the intake manifold. Otherwise, it's very easy to cross-thread it.

I'll stress once again to be careful not to over-tighten the manifold bolts/studs.

I haven't done this in a while, so I hope I didn't leave anything out and that it helps you.

 

[rickoregon]

MAP: yes, all 6 new spark plugs were uniformly fouled with carbon from too much fuel. None seemed more carboned-up than any other. I placed them out all facing me with a bright light and oriented in the same direction to get a good comparison. I had my glasses on, too! Also, I did the same with the old plugs that I had removed, which had been run in the engine for quite awhile after I initially installed the engine/tranny/t-case, and they, too, were uniformly fouled.

Regarding injector connections, I had cleaned those, along with all the other electrical plugs, treated them with De-Ox-it, and inspected the wiring. Further, I used my mechanic's stethoscope to confirm they were all "clicking" when the engine was running. When I get the dielectric grease, I'll re-clean, apply alcohol and let dry, apply the grease, as well - good suggestions. Thanks for "throwing out ideas," and I hope you'll continue as you see something that might benefit my troubleshooting efforts.

Tom R: I use PB Blaster all the time, and will do as you suggested. Thanks for the tips on the steering pump and other procedures. I'll make sure I don't remove the fuel rail from the donor intake manifold - good idea. I don't have any fuel line quick disconnect kits, yet, but they are on my list. Right now, I don't mind a little fuel leaking, because my tests are usually of such short length that there is very little fire danger. Once I get the original problem resolved, I'll be sure to install the kits and make sure there are no fuel leaks. Ooops, I ordered a Felpro intake/exhaust gasket. Well, I'll try to get an OEM before I do the manifold swap, but if I don't, I'll just plan on being ready to replace the gasket with the OEM next time around.. thanks for the tip. I'm going to try to get ahold of BG-44K and really do a strong treatment to the intake, as I can see looking inside that everything is pretty dirty. I checked motor and tranny mounts before installing - they were good. I always use a torque wrench on nuts and bolts when torque spec is given - if not, I go by size and grade. I'll be careful though. I've been told that petroleum jelly is good for o-rings. Anyone use something that's better? Thanks for the warning about the EGR tube connections. I'll take care to not cross-thread them. I've cross-threaded bolts and nuts in the past, and often that means a *lot* more work. Now, I'm pretty careful to make sure I can start with my fingers and *know* the threads are not crossed before grabbing the wrench.. Thanks for the step-by-step guidance. I'll begin yanking the assembly this afternoon (once the PB Blaster has had some time to do its magic).

Sensors are starting to arrive in the mail, so once I get the manifolds, injectors, and throttle body exchanged from the old (recently working) engine, I'll fire it up and resume sensor trouble shooting. It could very well be that one of the sensors is fooling the computer and making it send signals that are in error.. Or perhaps it's something else entirely! Much obliged, Rick

 

[rickoregon]

Oh, one more thing... when I had Kate crank the engine over, so I could look at the operation of the intake valves through the fuel-injector ports, the gas flowed out of the inlet line. Had to have her stop cranking. I'd already disconnected the ballast resistor, so I promptly pulled the fuel pump relay, as well. Surprisingly, when Kate resumed cranking, the gas still flowed! What's up? Is there something else I need to disconnect to stop the flow of fuel while cranking the engine over? I thought the fuel relay controlled power to the fuel pump.. I even tried disconnecting the power latch relay, but that didn't make a difference either. Could I have a problem with the relay wiring so that the fuel pump will run, regardless? What do you think? I'm a bit confused... as always!

 

[Tom R.]

Regarding the Felpro gasket, I've heard that it's a good one to use. If it's convenient, you might want to compare it with an OEM gasket at your local dealership.

The fuel flow seems odd to me, too. Maybe check that the wiring isn't shorted, effectively by-passing the relay? I just don't know enough about the fuel system theory of operation to know for sure.

 

[rickoregon]

Regarding the Felpro gasket, I've heard that it's a good one to use. If it's convenient, you might want to compare it with an OEM gasket at your local dealership.

The fuel flow seems odd to me, too. Maybe check that the wiring isn't shorted, effectively by-passing the relay? I just don't know enough about the fuel system theory of operation to know for sure.

I misread your earlier post stating that some members had good luck with Felpro. I'll look it over well when it arrives and see if I can compare to an OEM.

Regarding the fuel pump running with the ballast resister unplugged and the FP relay pulled, I guess I could have disconnected the pump at the tank. But I don't think it's suppose to run without the relay. Maybe that's part of my rich-running, backfiring upon throttle advancement problem. One thing I've learned about automechanics is that, just like the human body, systems are coupled and often more than one cause can create a problem.. I'll check for shorts in the fuel pump relay wiring.

PB Blaster works great... I removed the bottom intake/exhaust manifold bolts/nuts with no problem, other than trying to configure the right combination of extensions, u-joint sockets, etc to reach. I always try to do the hardest parts first.. Now I need to remove the EGR tube fittings, and I think I'll need to use a cheater on them!

Thanks for your help. -Rick

 

[satan]

thought...

What's your fuel pressure looking like - and is it controlling properly with the VACUUM portion of the regulator (when I leave the vacuum source for the regulator disconnected I get this exact response - idles well, but rich - crappy transition to higher RPM, then reasonable performance at higer RPM)...

Emulating a low vacuum condition at the regulator should cause the rail pressure increase (similar to a power-valve and/or accellerator pump in a carb) -- :dunno:

 

[MAP]

Just something to try... Although it appears the components for the 87 and 89 engines should be the same, maybe there's something different with the computer?

Why not try switching out the Engine Computer module from the 87 to your 89?

If that doesn't change anything... it's back to the checking fuel pressure and vacuum.

MAP

 

[rickoregon]

satan: the fuel pressure is at specs (33 psi with engine running and press. regulator vacuum line connected / 39 with vacuum disconnected). Thanks for the input.

MAP: Appreciate the idea. I was thinking maybe that could be a possibility, too. Major difference between the '87 donor Laredo and the '89 base model Cherokee are: obviously the year; '87 had a 242 t-case, '89 a 231 and now it has the 242 in it; '87 had cruise control; '87 had no-disconnect front axle, while '89 has disco axle which I've disabled using the washer-spacer technique recommended by members. I'll put it on my list to yank both computers (ECM and TCM) from the '87 and compare the numbers with the numbers on the '89's computers. If the other things I'm doing to the '89 don't help, I'll do a swap as you suggested. Thanks.

Here's status of the project right now: Using Tom R's procedures I've removed the intake and exhaust manifolds - waiting for the new gasket to arrive before installing the '89's original intake/exhaust manifolds and throttle body assembly..

Decided to order new motor mounts, after all, because there are very small cracks in the existing mounts, even though they only have 60K miles on them. Like Tom says, it's easier to do them now, with the manifolds off!

Also, following up on Tom's thought, I'm working my way around the harness, cleaning as I go, and even repainting the fender walls if I don't like the looks of them after the cleanup. I figure it's easier to spot problems with the wires, if everything is clean. I'm going to check continuity of each wire after I've done a close inspection and cleaned/protected the contacts. Only problem I have is that the wiring diagram I'm using is so tiny, that it's hard to read all the wire colors, etc. Anyone know where there is a higher resolution wiring diagram for the '89?

I'm also going to replace the MAP, O2, CPS, MAT, coolant temp, and knock sensors as well as the TPS, the coolant temperature light sensor (on the top left side of the head at the rear) and the aux fan temperature switch (in a small metal pipe section spliced into the radiator outlet hose) with new components. Will also install a new OEM thermostat and new relays for A/C, power latch, fuel pump, O2 heat, and auxiliary fan. Now, what have I forgotten? Anyway, I'll keep you all posted and thank you for sharing your wisdom. -Rick

 

[rickoregon]

Hello, just wanted to close this thread out by letting you know how it all turned out.... Once I installed the intake manifold/exhaust manifold/fuel rail/throttle body combination from the original '89 engine, all was fine. So, I'm suspecting it was the injectors that were not working well from the '87 donor engine. I'll replace the TPS with a new one and install some other new parts as well. But just wanted to let you all know that the Jeep performed well after the switch. I'm having another problem with it now, so I may start a new thread with that problem, if I can't find help using the search function. Thanks again for all your help back then -- much appreciated. This is a great forum with good help and friendly folks. All the best, Rick

--
Rick & Kate Johnson
Venice Ranch, Burns, Oregon 97720
http://home.centurytel.net/venice/

 

[5-90]

My first post to this forum, so hope I get it right.. I tried posting this yesterday morning, and it never showed up... strange.

I've been reading posts here for awhile and searched on all sorts of difficulties I've encountered in swapping an engine/tranny/transfer case from an '87 Cherokee (Laredo) with Selec-Trac into an '89 Cherokee that had Command-Trac. Both XJs have 4-speed automatics and the 4.0L I6. The swap has been done and the engine runs... at least at idle.

It wouldn't even run until I checked the basics: spark, fuel, air, timing and determined that the fuel pump 2" transfer hose inside the fuel tank was broken. Repaired that, and the engine starts and runs.

However, when I move the accelerator the engine stumbles, coughs, and backfires.

So I've started down the path of troubleshooting. Here's what I've done so far based on advice given to others here at :

-checked timing (distributor rotor points to #1 plug when #1 cylinder is at TDC on compression stroke)

-cleaned and examined cap and rotor

-checked firing order

-removed exhaust including cat and muffler

-checked fuel pressure (33/39)

-checked that all injectors are firing

-changed out 02 sensor

Now I'm at the stage of cleaning the throttle body.

I notice that when the engine is running, and I spray a good shot of carb cleaner into the throttle body and open the throttle, at some point the engine takes off and runs great - rpms go up as high as I want, and I've got great performance as long as I keep that throttle open. Even without adding more carb cleaner. But when I back off on the throttle to idle and then try again without carb cleaner, the coughing, sputtering, and backfiring is there again..

Any idea what might be causing this engine problem?

Seems to run ok once it gets up to a certain point in rpms.

I'm just trying to understand why a temporary application of carb cleaner will allow the engine to run well until I let off the throttle.

Any insights greatly appreciated. -Rick

Without starting at the beginning and reading the whole damn thread (sorry - gotta go pick up the other half in a bit, and I just can't be arsed right now...) my first impression would be the IAC (in the throttle body, next to the TPS.)

The fact that you're having trouble at idle, but you're just fine from off-idle to redline is what brings that to mind at first. When you're idling, the throttle valve is fully shut (not quite, but close enough for government work) and the idle air passage allows enough air in for the engine to idle. The amount of air through the idle air passage is controlled by the IAC, and that is opened and closed in response to changing operating conditions.

When you open the throttle valve, all bets are off - because the IAC just isn't involved anymore.

Spraying carburettor cleaner down there would be akin to the old "accerator pump" on carburettors - which provides a surge of fuel while the main system catches up. Theoretically not needed with fuel injection, but could be indicative of another malfunction I'm not thinking of at the moment - probably a sensor issue of some sort (MAP, IAT would be my first guess.)

Try removing the IAC and cleaning it before you get into anything else - might want to clean the IAC seat as well, since getting dirty there will cause issues. DO NOT pull on the IAC pintle while it's out, and DO NOT apply voltage to the terminals, since the IAC REQUIRES replacing if the pintle is unseated!

Try that - if it doesn't work, PM me the link to this thread and I'll read the whole thing (so I can filter it according to what else you've tried and what advice you've been given.) However, the IAC is the first thing I'd check, and further checks would be guided by symptoms.

5-90