XJ 4.0 - rough idle

[vaco]

I often see an information that rough idle is normal for 4.0 XJs and other Jeeps with this engine. I am not native English speaker and I am not sure what it does exactly mean. My XJ has an issue with idle since I have it, or at least I think it is an issue, unfortunately XJs are not popular in my area and I cannot compare it with other XJ. I would appreciate if someone could explain what is "normal rough idle" for this engine. My XJ has quite stable 750 RPMs on idle but once per 1 to 5 seconds there is slight increase/decrease of RPMs, it is really small, I have to look carefully at the gauge to see indicator movement, however I can feel the vibration and with open hood I can see the engine shakes each time this happens. Effect is mostly present when engine is hot, but not only then. Is that this normal rough idle? If not then what are possible solutions for that? What I have already replaced while fixing other problems:
- IAC
- MAP sensor
- TPS
- both O2 sensors and catalytic converter
- CPS
- cap, rotor
- oils, filters

None of these did affect my "bumpy" idle in any way.

 

[Tim_MN]

Regrading your other thread, 1997 XJ 4.0 - Ignition timing angle question, if the Idle Air Controller is functioning correctly, small noticeable variations in the idle speed are not unusual, or a problem.

The idle should be 750 rpm, plus or minus 50 rpm, any variations to 300 or +1200 rpm would suggest an Idle Air Controller malfunction.

If the idle varies slightly and engine does not stall, everything is normal. My carborated 1984 CJ-7 has an earlier version of the Jeep in-line 6 cylinder engine, and idle is bumpy, but it never stalls.

 

[vaco]

Ok, so I just need to get used to it. Thank you!
Also thanks to all users for patience. I am newbie to XJ and mechanics and have a lot of probably stupid questions.