Rough idle, shakes

Cant figure out what causes rough idle.
When started cold it starts at 1100rpm, soon drops to 750, and sometimes even lower and then it tries to even it out jumping to 1100 and back.
This is when its not moving, if I dont wait for the very low idle and start to drive, it is fine for first minute,but then there is sudden loss of power, no throttle response, nothing, but only for 2-5seconds max, and then its gone un runs fine (except rough idling at 750) until I restart the jeep, then the loss of power for couple of seconds every time once its restarted.
There is also shaking, its worse when cold.

Jeep is 1997 XJ 4.0 210000km (130k miles)
Automatic
242 transfer case

Things I have done:
- spark plugs, wires, rotor cap, rotor
- air filter
- new TPS
- new IAC
- cleaned throttle body
- fuel injector cleaner in full tank of gas

OBDII shows only missing battery temperature sensor code, which I am still missing.
Vacuum seems fine ~17


Which would be the next thing to try? I guess due to shaking there could be misfire?
- MAP?
- injectors?

I will get the missing battery temp sensor, but I guess that shouldnt affect idle

- update

while the idle was very rough, did the bluetooth obdII realtime information and the Vacuum values were between 9 and 11, I guess thats way too low and should check for vacuum leak?

Thats where I would start, by looking for a vacuum leak. I found, in the 96 I just got, that the hard vacuum line that goes to the vacuum ball behind the bumper had broken underneath/behind the battery tray. Spliced it with some rubber line and everything smoothed right out. Another good place to look is at the grommets for the PCV and breather in the valve cover. if they've never been changed you might want to have a new PCV and Breather elbow on hand as they'll probably break when your trying to get them out.


Edit: The o-rings on the injectors tend to get hard and shrink too. in extreme cases they can cause vacuum leaks too.

marts. said:

- update

while the idle was very rough, did the bluetooth obdII realtime information and the Vacuum values were between 9 and 11, I guess thats way too low and should check for vacuum leak?

Click to expand...

9 and 11 what???? No units make the data meaningless.

"OBDII shows only missing battery temperature sensor code, which I am still missing.
Vacuum seems fine ~17"

17 (inches of mercury IIRC) on an engine vacuum gauge is fine.

The OBD-II is likely reading the MAP sensor data for the vacuum reading, so if the 9 and 11 reading is same units as the vacuum gauge, then the vacuum line from the throttle body to the MAP sensor is bad, or the MAP sensor is bad, or the wiring-connector to the MAP sensor has a problem, or a combination.

Other vacuum leaks should only cause a high idle, or other issues, in my experience.