1993 s10 blazer dead HELP! HELP!

ok im tired of beating my head against a wall on this one..i bought a 93 s10 blazer that ran fine untill lately. it did have the SES light on. i had it checked and it was the knock sensor. but as i said it ran fine. i found out that the 4.3 vortec was from a 1991 blazer. i was driving and it acted like it ran out of fuel. and would not start for an hour. then it started right up but was running rough. so i changed the fuel pump and filter. after it started and idled fine but would miss out until about 25 mph then it ran fine. then about 2 hours later it died and wont start. ive checked the coil and it has spark. i have not checked the fuel pressure on a gauge but there is fuel at the injecters. i want to exaust all options before taking it to a shop for a knock sensor. any ideas would be great.

A faulty knock sensor will not cause a "no start" condition. Check fuel pressure and leakdown and loss of fuel pressure when it acts up.