truck running like crap need some help

ok so heres what i got i have a 90 s10 with a 4.3 my prob is that after i start it it seems to wanna die like its not getting fuel but i can rev and it seems fine until i let out of it then it fights to stay running i thought it might be my cat but i was wrong i had some test run and the lady coudnt figure it out i guess it was saying sensors so i changed all of them plus the fuel pump and filter could it possable be a vaccum pob any sugestions would be great its my first bagged truck and i havent even been able to drive so im open to anything thanks guys.

you can throw parts at it all day long, but its still just guessing.
whats the fuel pressure? fuel flow rate? check for vacuum leaks? did you check/clean the AIC motor/passages? does the TPS pattern look ok?

i have no idea how to check my fuel pressure or my tps patern and im not sure what aic is

IAC= idle air control solenoid. It is on the throttle body.

If it runs OK on the gas but does not idle good, like very rough stumbling like. then....

I would look at your EGR valve.

It could be dirty and sticking open.

I had a 93 4.3 and I had to replace two of them in 80,000 miles for the same problem!

This would cause it to idle like Poop!

Good Luck!

Check for a vacuum leak to that could do it mainly check by the intake gaskets and throttle body just spray some starting fluid everywhere while its running if its got a leak it'll rev up when you spray near it.

thats whats really throwing me of because i changer egr tps iac map temp sensor my throttle body fuel pump and filter im just lost unless its a vaccum problem