My 90 was doing this exact same thing. It ended up being my ignition module inside the distributor. I pulled it all apart and there was a lot of rust on it. Swapped it out, did a tune up, and it ran like new. Echlin PN ECH TP25.
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I believe I just used a cheapie at the time . unfortunately that's been a couple years, and i don't recall . And I didn't really have it long enough afterwards to find out , a deer made sure of that.
I'm planning on installing an ac Delco pump in my 91 when I can get a couple guys together to help me lift my truck bed off lol.
Here's a really good article of a guy installing a pump into his truck .
https://www.thirdgen.org/forums/tbi/612473-tbi-fuel-pump-upgrade.html
There's a bunch of info on that site so if it's and electrical gremlin you're after then I would go searching over there . I mean our trucks are essentially giant Camaros really, lot of the same electrical systems. Same engines and transmissions .
I have also seen a bunch of write ups on replacing the fuel pump on this website too. So do a bit of searching and you'll find it .
Just my 2 cents; my '90 Silverado TBI,383 stroker was doing similar things (especially the starting fine cold then crapping out part) it was the fuel pump.
Don't need to remove the tank or bed to replace the fuel pump. I have a 96 C3500 Silverado CC long bed. I removed the bed bolts on the driver/tank side and loosened the bolts on the passenger side. Disconnected the wire harness to the tail lights and the ground and used a bottle jack setting on the leaf springs and some wood blocks & tilted the bed to about 35 degree angle. Replaced the pump easy peasy.
My 90 was doing this exact same thing. It ended up being my ignition module inside the distributor. I pulled it all apart and there was a lot of rust on it. Swapped it out, did a tune up, and it ran like new. Echlin PN ECH TP25.
The symptoms you described in the first post sound exactly the way my 1988 truck acted. I ended up replacing the pump, but I probably did not have to. It turned out that the short rubber fuel hose above the pump was cracked from reacting with the ethanol added to the gas. You mentioned being short on cash, so that is what I would change. It is a cheap part to throw at the problem.
Like Stephen said above, it is not all that hard to lower the tank or raise the truck enough above to get at the problem. I lowered the full gas tank using a Toyota scissors jack under a make-shift wood cradle.