I recently bought a 1995 XJ with the 4.0 HO motor and AX15 tranny. Running pretty rough. After looking through these threads, I started fixing things. Made a big gain on improving idle when I changed the plug wires. I had already changed new distributor cap and rotor. Turns out the #6 wire was hit or miss.

Then I changed out a busted front pipe and put in a new O2 sensor. Ran even better. Then I started tracing every vacuum line and looking them over. Found 3 leaks. Again....the idle got even better. I had an issue where it would cut out under load at about 60-65 MPH. I went and bought a CPS and a can of Seafoam and rented a fuel pressure tester. The fuel pressure is at 37psi from idle to 3K so that eleminated the pump/filter. Then I poured in the can of Seafoam and hit the freeway. The stumble cleared up! I returned the CPS for now and my rig is running right!

Oreilley Auto parts has the fuel pressure tester for rent....put down a deposit and return it for a full refund. If you guys have issues like I have...just get started and check for vacuum leaks and do a tune up. For less than $100 you might hit on something and get your rig running right. Stay the hell out of the deep mud and water and check/change fluids regularly.

Thanks to all the threads addressing problems that helped me out.