I've got a 90 xj 2.5L with 5-speed 2wd and just recently its started osiliatcing at idle and bogs down really bad when im driving it. Its not the the point where i can't drive it. I had to move it last week to get it to my new place and I couldn't go over 45 at full pedal. When it bogs down if I feather the gas heavily it starts to clear up and accelerates. I am thinking it could be the MAP sensor or TPS but i don't wanna spend like $150 in parts for it not the be the answer. If anyone has any idea what it could be or maybe confirm my theory it would be greatly appreciated.

 

I've got the 2.5L as well, and I have the same problem. I did a full tune up- new plugs and wires, cap and rotor, injectors, fuel filter- and it still runs ****ty sometimes. I lose all power with the gas in, if I floor it a get a pop from the engine compartment and it runs good. Or i can let off the throttle sometimes it won't do it before shifting to the next gear. It's also completely unpredictable. I drove 500 miles last week without one issue. And it started up again today. I hope that wasn't too discouraging! I haven't got any help on here tho- just common tips like gas additives and basic engine service.

 

Try pulling the throttlebody and cleaning the heck out of it.Also check all of your vacuum lines and your timing.Check your distributor for any moisture.

 

Thanks for the reply. I tried to adjust the timing but they're no give to turn the distributor. Is there some sort of button to push to get it to move? Also, I kinda gave up on the timing being a possible issue because I was told on here and from a mechanic friend that if the timing is off the backfire would be pretty bad- or at least fairly consistent. I'm going to look into cleaning the throttle body and checking vacuum lines. I'm a novice mechanic at best.. but I'm learning! XJ's seem really straightforward.. and this forum has been a great tool to use with the service manual.