I'm Ben, I am new to the forum. I bought a '99 TJ at the beginning of the summer, it has run well, hasn't given me any problems. My one issue is that the revs will hang up around a grand or so when idling occasionally and on start up, I just rev it a little and it dies back down to where it should be, around seven or eight hundred rpm.
I was hoping someone would have any ideas to why it is doing this? Is it common problem? Don't know if it matters but it is a '99 2.5L manual trans.
An even cheaper and easier way to start is to clean in and around the throttle body and the parts that attach to it. These spots get gunked up and since those sensors are what controls our idle it can effect it or make it not consistent at times. Get some carb/throttle body cleaner and clean it good. I always completely take it apart if I'm doing this to make sure you get in all the hidden areas. Its an easy 30-45 minute (at the most) job.
Edit: Also, if you search on this forum about this problem you'll find many results. If cleaning the throttle body doesn't work next step is to check all your vacuum lines for leaks.
This is frequently the sign of a quirky TPS sensor...costs around $50 at the dealership (maybe a lil more). You can get them cheaper at Autozone and the like but I've found the cheapo ones tend to be very quirky like that.
Also can be the sign of a vacuum leak, but since it goes away after you rev it, I'm leaning towards the TPS sensor...I had the exact same problem a while back. TPS sensor solved it.
"We don't build great brakes because we think you don't know how to drive, we build them for the guy on the road in front of you that doesn't." - Black Magic Brakes