Got a puzzler, 99 Xj was running and idling fine. Out of the blue right around 210 the oil pressure gauge dropped to 8psi and stays there. No fluctuations when revved. At the same time the idle becomes rough , Jeep will barely move on its own power. Let it cool and it runs great, run it down the street and back and the idle gets rough and will barely move.
I did swap a working oil pressure sensor , IAC and TPS on to it with no change. Jeep has never had any oil pressure issues or has it been drowned or beat on terribly. When the rough idle starts , fuel pressure drops to 20psi. Starts right up and runs after cooling. Never been over heated.
Literally did a 5.5” lift the night before and it ran great. Got up this morning, put a tcase drop on it and nothing but trouble. No CEL either. Any help is appreciated.

 

Thanks for all the help, JK! I may have figured out the issue(s). Every time I checked the fuel pressure it was back to running normal. So hooked the fp gauge up and bled some gas out while it was running and it never recovered. It continued to stumble. So to tomorrow we’re going to put a new fuel pump in. I believe the oil pressure sensor is seperate issue. Here’s a picture of the little beast. Not mine, belongs a friend. 5.5” of lift, 4” full traction Tj coils, unknown leaf springs, jks adj upper, off brand lowers and 33x12.50 procomps.