Hey guys, so just recently I had time to actually work on my jeep from damn engineering school and figured out some issues with it. One of them is when I start it up for instance, it will rev all the way up to 2,500 RPM and slowly work its way back to 750-500. It will pause momentarily at 1,250 for a couple seconds and like I stated work it way to normal idle. However, sometimes it will bobble between 500-250. In addition when I put my jeep into park or neutral after a drive it will shoot up to 2,000RPM and work its way to 1,000RPM. Anyways what I did was I unplugged my MAP sensor see if anything happened and it did so I knew it wasn't that sensor and tried my Idle Control valve and nothing happened. In my mind I was thinking that was the issue I replace it and nothing changed so my theory right their failed. I thought about my PCM next but, I replaced that 9 months ago with another ZJ with considerably less miles and it fixed other issues I had previously with it. Finally I resulted to my Vacuum lines I took some brake clean ran out of carb cleaner and sprayed at various locations along my vacuum lines. Nothing happened when I did so the only area I haven't checked is under my battery tray. Also I got a question regarding a certain line it's to the left of the MAP sensor on the 5.2L is that a fuel line or vacuum?
It would be awesome if you guys can give me input on what possibly could be wrong with it or double check my lines once more, etc. Help will be very much appreciated!!