Oscillating Idle

'88 4.0 Auto.

My XJ is starting to give me some oscillating idle, doesn't seem to matter if it is warm or cold. So far nothing serious, it otherwise seems to run strong, just started doing this a few weeks ago.

It has also shut down on me a couple times while sitting at a red light, starts right up and runs fine afterwards.

Vacuum leak maybe?

TRy changeing your 02 sensor located on your exaust header.thats what mine was.

88trailcrawler said:

It has also shut down on me a couple times while sitting at a red light, starts right up and runs fine afterwards.

Click to expand...

EGR system.

The kid just came in and told me it died on him again today. with "black smoke coming from the front" He waited a minute, restarted it and it's been fine all day.

It is tough to tell what he means by "black smoke coming from the front"

88trailcrawler said:

It is tough to tell what he means by "black smoke coming from the front"

Click to expand...

Major manifold leak???

88XJSport said:

Major manifold leak???

Click to expand...

Exhaust manifold? Could that occur randomly like that? I have been driving the jeep daily for a few months and took it on two long day highway/trail runs, never had any bad signs.

Plus I drove it around the rest of the day today with no issues. I am thinking a sensor or vacum connection is the culprit, but have no idea where to start.

I will look into the O2 sensor, Can you elaborate on the EGR system, any other input would be much appreciated.

Sorry, I don't really have any experience working on cars.