I have an 02 KJ I just bought. I negotiated the price quite a bit because of the jeep idling high on the test drive. Seller said it was a new issue, and then it didn't do it for my first week or so of ownership. Now it is revving to 3k+ at startup, then it hunts form 1500-3000. When driving down the road in gear it feels like cruise control is activating, so when I let off the gas it takes a second, so it ends up being really jerky going down the road. It just got bad last night and is still doing it this morning, I won't be driving it until it's figured out. Doesn't really feel like a vacuum leak as I've experienced that but who knows. No MIL currently, and no codes pending. I don't have an advanced enough scan tool to go much further than that. Doesn't seem like it should be to hard to diagnose, but since this vehicle it new to me and I don't know the idiosyncrasies of the liberty, I figured it would be a good idea to talk with some other KJ owners as I proceed. Anyone have anything to add?

In case anyone comes across this in the future, my issue was solved by replacing the iac motor. We diagnosed by removing the part from throttle body and commanding it with a scan tool. The iac became extremely hot and would not actuate. Funny thing is that while driving with scan tool attached, the vehicle would symptomize upon pushing the gas pedal. When watching data values, the purge solenoid was being activated, essentially inducing a vacuum leak much like the iac motor does, and causing the revs to go up to 4k. Funny how a bad iac would cause the purge solenoid to activate also, but the part is replaced now and the vehicle runs well. Hope this helps someone in the future.