My CE liight has been on and i finally checked it out, and i plugged it in. 2 codes came up, but this is the only one i remember; P0171. System Too Lean (Bank 1). but before you look that up, i know i have a crack in my manifold, and i understand it needs to get replaced. but whenever my engine heats up to normal temp, ill keep my foot steady and my rpms will just drop, then shoot up, and go up and down over and over while i keep my foot steady. but if i go over 3k it wont do it. after i let the rpms go back down it will want to die so i have to either put my food down and feel my jeep jump and jump and jump or go 3k plus on the rpms and go flying by. It does become very difficult to drive this way. especially when their are people in front of you.
If you were on the road next to me or in the passenger seat, it would look like i would stomp on the pedal and right away let go and jump on it again and let go, it is very frustrating so if anyone could help i would appreciate it! i will find the other code later and post it in an hour or two as I am working