Engine Performance problem
1991 Chevy Truck V8 Two Wheel Drive Automatic many miles
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cranks and automatically cuts off over and over, changed computer brain, map censor, pick up coil in destributor, cap and button, cleaned o2 censor, new spark plugs, ran code check on truck and says nothings wrong, still doing same thing. help!!!

check fuel pressure and ignition switch.
Let us know
Put a meter on coil B+ and see if voltage goes away when you release key to run position

we''ve tried everything, someone told us it might be the distributor but it wasn't, they think the timming may be messed up but not sure we are going to find out today, um I need a list of everything that could be it, thats how were doing this now, a shot in the dark kind of thing, we've replace just about everything, but we may have missed something

we've checked the ignition switch also checked fuel pressure neither were the problem, and we've replaced the coil , but still does the same thing, but after a long amount of time cranking it up and it shutting off it will run longer and longer until it seems to be running fine then it shuts off but after every time we crank it up it run;s longer and longer

can someone please help