DISCLAMER- yes I have read eons and eons of threads on this and have done a crap ton of research. This is a special monster. Hello everyone. I’m new to here. I had a few questions maybe someone might be able to help me pin point. Basically as the post says, I’ve got some strange idling going on. For starts I’ll say, I own a 97 Cherokee sport with the 4.0l 199k on it. To better dive into this. Whenever I start it up it idles at about a grand or so and the drops down to around 7 and half after a min or so, and then it’s begins to slowly drop lower and lower till it’s around 500. It begins sporadically misfiring here and there, nothing significant you can only hear it from the back end of the car, or in the cab. So I did some work. Of course the usual. Spark, rotor, plugs, ignition coil, cleaned the throttle body, cleaned the IAC, tested the TPS, tested fuel pressure (read at 45-50 psi when turned on by jumping the pump. And then of course while it’s running as well. I did notice that the pressure went down to around to 40ish after 30 seconds, and then dropped to 30psi after about 2 mins, don’t think it’s the issue. But I wanted to note it) then I checked spark plug gape, read at 0.35, so it’s fine. After that I did a test on the injectors to see if they were spraying ok. Definitely not atomizing well, so I have some multi points on their way. And that’s when I noticed another really strange thing. After I did all that and tested the injectors. I started the car and and gave it a little gas and it would spike up to 1,500 then foot off gas and it would bring it down to 1000 and then after a second or two drop down to 750 and then start it’s normal rough idle. Then I did it another time. Same thing happend. And then another. This time it spiked up and began to climb. 1500, foot came off the pedal, then it spiked up to to 1700 then 1900 and then 2500 (all in 3-4 second steps. Not a continuous pull) so I shut it off and called it a night. I figured I pissed it off enough and got back to it the next day. I then checked it and it seemed to “work its self out” and didn’t climb anymore but continued to step down after reving to 1500 the foot off,brought its self to 1000 held for a second, then to 750 and then down to rough idle again and misfiring BUT WONT DIE. So what I’ve narrowed it down to is, map sensor, crankshaft position sensor (maybe? I feel like I’d have more extreme things going on if it’s that), cam shaft position sensor (dizzy does have a little play but I feel like that’s normal), o2 sensors, or a good ol tiny hidden vacuum leak, or perhaps engine coolent temp sensor or intake temp sensor I’m not sure. Oh it’s also worth mentioning I did a vacuum test and it read about 16 pounds of mercury, and was in the labeled area late timing. So I believe I’m resulting in timing issues because a sensor is trying to compensate. or a waky fuel, air, spark ratio. If you have any insight or ideas please let me know before I start firing the parts cannon at this.