Hey Everyone so i have been dealing with this issue for probably about 2 or 3 months, just haven't had time with work to sit down for a day and diag it 100%, so im going to go through what i did do after i say what is happening. Yes i had searched the forums but it seems that i have replaced everything that everyone had solved there issue with

So the XJ would run great and one day my buddy was driving the truck said the truck was missing it seemed like which wasn't a big deal he brought it over had a code for an O2 sensor, so I changed both of them and it didn't do it again for some time. I figured it was nice out one day ill take the doors off and drive the jeep ran great for about 2 hours. while i was driving it miss/hiccup at any speed or RPM, then about 5 minutes later it died with a crank no start. towed it back to my house and the CPS wasn't reading so i replaced that with a Autozone one ( yes i know i shouldn't have done that ) the truck ran great then a week later while driving around running some errands it missed again. got it back to my house and then it wouldn't start again. Got a mopar CPS this time and brought he other back as a warranty and got a credit. driving the truck now it is still missing/hiccuping but it never stalls just rough running whether at idle or driving. Changed plugs wires cap and rotor since they hadnt been done in a while. That didnt work, i put a new distributor in since i thought maybe it was the sensor in the distributor shutting the truck off, nope still having the same issue. Then i read TPS could have problems figured well ill change that since it was a few buck and still doing the same problem. I am lost with this truck. I had a scan told on it viewing live parameters and did not see anything out of the ordinary.

So over the past i would say 8-9 months i had done
- Both O2 sensors
- Mopar Crank sensor
- Plugs (autolite) never had a problem with them before
- Wires (duralast)
- New distributor (duralast)
- New TPS (duralast)

Truck has 190k on it and has always been go and i never had problems, the truck had a new Bosch fuel pump put in about 2.5 - 3 years ago and i checked fuel pressure it is about 40 KOEO and while running around 35, i am going to change the fuel filter Tuesday after work but just want to get some ideas on what to check.

The truck still runs and drives, and it does not die out neither, just very rough running with a miss or hiccup here and there and then will driving the truck light throttle or heavy it missfires and backfires non stop

 

Let it run for about 5min. then carefully pull the spark plugs (hot..) and inspect each one noting which cylinder they came from. Check for fouled or wet plugs (fuel soaked) I suspect a bad fuel injector. Hope this helps some Good luck and let us know what you find.

 

Those fuel pressure numbers don't look right. They should be closer to 50 KOEO and should not change that much while running. Your symptoms are also consistent with a fuel pump that is faltering.

Also when you had live data from a scan tool did you look at your short and long term fuel trim numbers? They should always trying to be close to zero. +-3% is pretty normal. Higher numbers indicate that the computer is trying to compensate for too much air, or too much fuel. They are probably the most helpful live data for you to have your hands on while troubleshooting a problem like this.

 

Thanks for all of the input everyone I am going to try some of tests and confirm the readings I had and will test the suggestions I really hope I figure it out soon and will keep everyone updated ... Also last time I changed the plugs the truck was warm after running for a while the sitting for about 30 min and they were all bone dry no signs of excesse fuel.

 

If you checked the plugs after sitting for 30min, there probably wouldn't be any.