About to set a match to this '91. You guys have helped me out in many ways but my issue persists.

Started out having random stalling issues and then intermittent crank/no start. Here's what we've done
1. Replaced fuel filter on the rail (had to cut steel lines, add compression fittings and new rubber hoses) that job needed doing and it's still working fine.
2. Found the 3.9L was '180 out' so went ahead and installed a new Distributor, cap, rotor, plugs and wires, coil and the firing order and timing is set.(this also needed doing but didn't stop the intermittent stalling)
3. Replaced TPS
4. Replaced key cylinder and ignition switch
5. Replaced ISC motor/valve
6. Finally changed the fuel pump and the tank was clean inside.
7. Hosed down the ECU connection with electrical cleaner.
NO TROUBLE CODES
8. New Battery and Terminal connectors
The damned truck starts and runs when it wants to. One day i will go out there to start and let it warm up(afraid to drive it and get stranded). Other days i go out there and it's back to crank/no start. One day it starts right up and idled but when i stomped on the gas to rev it, it died then back to crank/no start and it was in that state for 3 days. Today it started right up.
Today i realize we never replaced the Temp sensor; i read where you may not get a code for that. I am tempted to replace the damned ECU as well but my nerves and wallet can't take another disappointment.

After the fuel pump job, i drove it and it shuddered a bit so i stomped it and drove cross town it smoothed out and ran like a scalded dog. It handles great and i want to keep it but it's making me physically sick over here.

Can't afford or even find a real mechanic and i'm useless. Hoping someone here might have a new thought on it.
Thanks bunches

 

Need three things for it to run, fuel, spark, and air. Air likely isn't the problem, that leaves spark, or fuel. See which one you don't have when it doesn't want to start.

 

My buddy's rarely here at those no start times and i need to go ahead and buy a fuel presure gauge i guess and a spark tester i can work alone with. thanks

 

I just can't get my head around it. how can the truck be just sitting undisturbed in a no start state and the next day it starts like nothing's wrong. shouldn't this simply point to a bad part?

 

CHECK THE NOTORIOUS SPLICE on the driver fenderwall, near the underhood fuse box. I'd bet that's it. Dampness/ moisture in the air (or not) at different times will make an iffy connection even more tempremental.

 

I have a question about what you said you have done to truck...
Where you said that the engine was 180* out, had the distributor been removed? Timing chain been futz'd with? If no to both then I have no idea how this thing could have been 180* out of time. No way possible unless one of these 2 things has been apart.

 

We did check that splice on my 94 model but it was fine. it hasn't occurred to me to check on this 91 so thanks for reminding.

 

My mech buddy used the term 180 out and i can't remember the circumstances. he said people will do that as a last resort to get an engine running. when i talk to him again i'll ask. thanks

 

ASD relay will cut the power to the fuel pump, and coil. Next time it cranks but doesn't start listen for the fuel pump, and a spark tester would be a good idea also, takes 2 people. One to watch for spark, and the other to crank the truck.

 

I don't think to listen for the fuel pump on the times it's no start. i'll do that next time, thanks. Just cause it was a cheap part, i did order a new asd relay and i'll put it in tomorrow.