Revs Low when idle

[myc1972]

Hi Guys!
It's about My 1999 Jeep Cherokee XJ 4.0L.
It is winter and getting cold here in Northern Illinois. My Jeep started to act strange. When it is colder weather it started to sometimes idle really low where it almost want to die out, but it has not, a couple of times it reved up really high by itself, in park.

It only does this rarely, but am afraid it will get worse. What could be the causes of this?

Thanks!

[4.3LXJ]

The first thing you need to do is pull the idle air controller on the throttle body and clean it and the area it rests in. If that doesn't do it, I would check your O2 sensor. How long since it has been changed?

[myc1972]

The first thing you need to do is pull the idle air controller on the throttle body and clean it and the area it rests in. If that doesn't do it, I would check your O2 sensor. How long since it has been changed?

I just bought my Jeep last year so I don't know if the previous owner ever changed the O2 sensor......or what other work he had done to it.
Does it have two O2 sensors?

Thank you so much for your help!

[4.3LXJ]

I believe so