I have replaced the fuel pressure regulator, ecm,prom.distributer,rotor,cleaned tbi injectors, pickup coil, ignition module but my blazer starts up great but dies in about 5 seconds. I have fuel pressure, the pump runs but the onlt time it ran at all was when i switched the tbi injector wires from one to the other. I put the wires back and it ran for a day. Now nothing will solve the problem. The tps tested good and if you turn the key off and back on it will start and run for about 5 seconds. I have a good spray from the injectors during the 5 seconds it runs. It is like the computor is not sensing the engine is running after the initial start. If you pump the throttle fast you can keep the engine stumbling for a short period but the injectors are not spraying

 

I was having the same issue with my 86 s10 pu, 2.5 4cyl.

I changed alot of sensors and wires, however I did not replace the computer.

You might want to get a computer from a bone yard first and try that, check your fuel make sure you don't have any water in your fuel.