First off I have a 91 XJ with a 4.0 and the AW4 tranny and its got 180,000 miles on it. Ok a few weeks ago I was pulling up to a stop sign and I noticed my RPMs drop really low and the engine almost stalled but it recovered. The next day I was leaving my house and got to the stop sign and it died but it started right back up and I got it home. I did my research and I went through and replaced my TPS and MAP sensor. Drove it for a day with no issues. Then the next day it died on me again. It started right back up and I got it home. I checked my spark plugs and wires. My 02 sensor is only about 4 month old and my CPS is less than a year and I got all my parts from the dealer. I was stumped so I took it to my mechanic and he said it felt like the solenoid for the torque converter was failing to release so they replaced it. Drove it home 15 miles and it ran fine. took it out the next day let it warm up drove it a few times around the town then as I was pulling into my driveway it died on me again....It started right back up and I parked it. I cant seem to figure this one out...

 

I would start by making sure that you have a strong blue spark. Also make sure that you have the correct fuel pressure. Your 91should have 39psi at the fuel rail. You can rent a mechanical pressure gauge at most parts stores. Check those things out and let us know what you find and we can go from there. Hope this helps.

 

I read your post about the cps only being a year old but that behavior is dead on for a bad cps. I would change it anyway along with checking the fuel system as the other guys mentioned.

 

Thanks I'll start w the fuel pressure. Then the CPS. Is that 39psi at idle?

 

Yes.