My buddy has a 95 xj with the 4.0, when going down the road during accel it will buck around 2500 up on rpm almost like turning the key on and off. Kinda hard to explain but when it is cold outside it doesn't do it or a least not yet. Any help or ideas please because we are just confused lol

 

Sounds like a gas problem, When was the last time he changed fuel filter.
Then injectors, Might put a little sea foam in gas and see if it cleans up.

 

Sea foam yes lol already done fuel filter no do u think that could be it just that simple

 

A sign of a failing CPS is failure when it gets hot............

 

I was kinda leaning towards that. I put another in but didn't work so now I've got another one to try