!!!! HELP PLEASE !!!! ENGINE PROBLEM!!!!

Ok guys, i need all the help i can get. Here is the deal. I have a 96 silverado with a vortec 5.7 motor, the truck has been running like crap. Ive changed the plugs and wires, changed the TPS and IAC. The truck was idling high but once i changed the IAC it fixed that....now the truck will die after i let off the gas while driving? It idles fine when its sitting but when i drive it down the road and let off the gas it dies... Please, this is my daily and i need it to be fixed. Im gonna check back in the morning and if noone has replied i guess its off to the shop...=( Here is a pic of it...
 

Edited: 8/5/2010 5:50:27 PM by pmiller

Map sensor? Last time fuel filter changed? And when u say u let off the gas, are you pressing the brake or just coasting?

check the fuel pump these things are notorious for fuel pumps ive done 4 in mine in three years

Have youve check to see if it throwing any codes?

You said running like crap, but then you pretty much only described an idle problem.based on the dying out when letting off the gas: check for vacuum leaks, then check to see if you throttle body is dirty (may have been what clogged the iac valve if it was bad since you said it made an improvement on the high idle) 

havent checked the map sensor. not sure when the fuel filter was changed, not throwing any codes, and im gonna clean the throttle body again just in cast. I think it might be a faulty iac. How can i check and see if the fuel pump is working correctly?

i would also replace the fuel filter just because, ive seen some fuel filters that will make a vehicle not run at all if they are dirty, as soon as they get replaced the car runs great again.

check the fuel pump u need a pressure gauge drive it when the problem occurs see where the pressure is at