Cant thank you guys enough for all the info. I'm gonna get started on this witch hunt this weekend. I'll update any progress. Thanks!

 

so today I go outside I clean the grounds and battery terminals and crank the car up it starts up on the first crank now but will have a high idle or random idle it will just fluctuate from 1000-2000 rpm when it goes under 1000rpm it will stall and die out sometimes it restarts itself sometimes it dies. The engine sounds like it’s rapping and rattling. Any ideas anything would help.

 

Duuuuude... I went through about a 2 year process because of a bad crank sensor. First, it's a great place to start to find a solution to your issue. Second, do NOT buy a replacement from AutoZone. Any other store will probably do. Also, be careful not to drop the bolts into the transmission housing... you can retrieve them with a magnet, but it's a pain.

My 1991 XJ was going through intermittent stalling while driving, usually while driving slower or in traffic ~ 35mph. Sometimes it would restart, and other times I'd have to leave it where it was or have it towed (off of a freeway on-ramp...) I replaced the crank sensor and continued to have issues. If you can unplug the sensor and plug it back in and it magically works, it's probably a bad part and you can easily end up with a bad sensor straight out of the box. It's impossible to tell until you install it. In the end I replaced everything down to the full distributor before trying another new crank sensor from Napa, and it's run perfectly ever since.

 

I don't recall which Napa CPS finally saved my Jeep, but I have been unable to get Mopar replacement parts because I rock a 1991 and was told by every mechanic and dealership I called that they don't make parts for models that old anymore. However, moving on to Napa parts has worked really well for me. No issues at all since I stopped going to AutoZone. Definitely recommend Napa parts generally if you can't get your hands on Mopar. I was also having a lot of fuel pump / gas tank pressure venting issues and picked up both a pre-release gas cap and fuel pump from Napa that worked like a charm.

 

So today I checked and cleaned 3 grounds. The oil dipstick, the battery, and the braided one from firewall to block. Also cleaned the negative terminal on battery. It cranked right up and I let it idle for 10 minutes. Then I turned it off. Came out 5 min later and it's back to ****sville doing what it was before. So I disconnected battery again let sit for 5 min, connected battery back, still ****sville. What, the ,****.....

 

I had to put on new pigtails for TPS and IAC because the connectors were **** and when I went over bumps it would freak the throttle out and sometimes die... But my biggest problem was a ****ty cps and then another ****ty cps cause I had a mechanic do it... Now its a mopar and it runs right. Just be careful w the pigtail wire colors.

 

I've heard this before, that the CPS can come out of the box bad. The price difference is significant

 

We hear it all the time on this forum, and the same on other Jeep forums. Bad out of the box, bad in minutes, days, weeks, a few months. This is one part where it does not make sense to try to save a buck. Bite the bullet and pay the dealer.

 

Same thing with my Mopar backup light/neutral switch. I've had several bad out of the box. Never did get one that works. I had to add a push button on the floor kinda like the floor headlight dimmer except it doesn't stay on when you remove your foot.

I'm sure glad we got cheaper parts from China because parts that actually work are so over rated.

 

Well replaced CPS, and still acted up. Searching for other grounds, I found not 1 but 2 loose ground wires. Snuggled them up, and not only is it running fine, but my transmission shifts a little better, and AC gets cooler faster and AC clutch isnt cycling anymore.

 

Those freaking wires that ground to the dip stick mount.

 

There I was driving down the road and the engine just quit. No warning or symptoms. It just died. It was the CPS. I bought a $45.00 cheapo from Rock Auto and got exactly 3 miles out of it. I bought another from a local parts store ($75.00) and that was 4 years ago, IIRC, without further mishap. The thing is inexpensive, with a very high probability of being the only cause of the problem, and takes about as much time to change as it does to ring out grounds and harnesses (to no avail). Rule of thumb; the sensors in any OBD2 system should be changed regardless of their current serviceability at 100,000 miles.

 

Did your acceleration suck when it went out? Mine still isnt where I think it should be. I have a wrangler on 33s that has more acceleration than my XJ on 31s. ZERO *****

 

Try putting your old CPS back in...see if that helps with the acceleration issue.

 

That's what I have in there now. Once I found the loose ground, i put the old one back in to see if it worked. It did, so i took the old one back