Hello to everyone who also owns the single best and coolest vehicle available. I have an 88 comanche and I'm having an odd issue that I can't seem to figure out. A couple days ago I replaced a leaking thermostat housing gasket. I took it on a test drive to get some of the air out of the system and noticed it was bucking a little. I took it to Auto Zone to get the battery and alternator tested and they tested great. I figured I should just go ahead and baby it home, which was about 2 miles. I was cruising down the road when it just died for a second and came back to life and backfired like a 12 guage shotgun blast. This is the first time since I've owned it that it's backfired. Just as I made the decision to pull into the next parking lot, it did it again, this time it exploded the muffler. At this point it barely had enough power for me to slip the clutch enough to keep it rolling in 1st gear. I did end up having to move it a little further into the lot and this time it started to die like it did earlier except a plume of white smoke came out of the breather box. Now when I start it, it will idle fine for a few seconds, then it will surge between almost dying to normal idle. It doesn't surge up and down either, it idles for a few seconds and almost dies once then repeats until it dies for real after a minute or so. It sounds like it's having trouble staying running like it's too rich or something.
So far I have:
-Replaced a very sooty oxygen sensor - no catalytic converter
-Cleaned and checked plugs
-Cleaned and checked injectors
-Tested the coolant temp sensor towards the bottom of the block
-Tested the intake manifold temp sensor
-Tested the MAP sensor - after the backfires, the line to the MAP sensor was broken so I replaced the line
- Changed fuel filter
- Compression check - 150psi on all 6
- Fuel pressure check - 30-32psi while running
- checked bumper vacuum ball
- visually inspected anything I could see while fixing a couple little vacuum leaks along the way
A little history right quick. I've had this truck for 8 years. I pretty recently installed a remanufactured 4.0 in this it and replace all the coolant system and most all the vacuum lines and sensors while we were at it. For the most part, everything under the hood has about 20,000 miles on it. This is usually my reliable vehicle so I'm not sure what's gotten into it. Also, it has driven perfect multiple times a week until that day, which was about 4 days ago. Other than changing that one gasket, no changes had been made between it running like a top and the day I have described.
Has anyone experienced this or a similar issue that can point me in the right direction?