I have had a problem with my jeep for over 2 months now and can not figure it out sometimes it will run fine and sometimes it dosen't. sometimes after start up and the first few minutes of driving it will stumble and idle real bad at redlights. Its a 1999 sport auto 4.0l with 106,000 miles. For the longest time it would run like this and not trigger the check engine light until two days ago it happened at a red light it was running fine then it was like someone flipped a switch and it began idling pretty rough and the check engine light came on I went down to auto zone to have it read out and it throwing code p0108. I went down to the local junkyard and pulled all the sensors off of a throttle body from another 4.0l and I even removed my throttle body and cleaned it good and threw it all back together and checked for any vacuum leaks witch I didn't find. I reset the computer and cleared the sel and it ran good for about 2 hours while I was out tonight until I pulled up to a red light right before I got to the house and boom it started stumbling again and idling like crap. Does any one have any ideas I'm starting to think I might have a manifold leak somewere and will have to figure out a way to test it tomarrow.