I recently bought a 90 model cherokee renix laredo with 150k miles. everything is fine except for the idle. when it first starts it runs fine at around 7-800 rpms then after about 3 minutes of warming up it goes up from there, it'll jump to 1000 then all the way to 1800 then back to 1500 fluctuating, then after it reaches operating temp it wont leave about 1700 rpms, it sucks driving down the road trying to stop the thing. i've replaced the tps and the IAC. The Tps cured my shifting problem, wouldn't shift out of first gear unless i took the fuse out and shifted manually. What else should i be looking at?