This is driving me crazy. I have a '96 Sub with about 167,000 miles. I have replaced the fuel pump I don't know how many times. After the replacement it runs fine for while then starts to run rough enough that my wife is afraid to take it to the grocery store. Last replacement was with the, "New, Improved Turbine" fuel pump "Guaranteed to eliminate fuel pump problems with GM trucks." I have replaced the: cap, rotor, wires (Premium, best, most expensive I could find), plugs, EGR, all O2 sensors, and the fuel filter. The parts guy at Car Quest suggested that I put dialectic grease on the relay terminals and fuse for the fuel pump. He said his brother did some research and found that GM recommends this to prevent moisture related electrical problems specific to the well known fuel pump problems. Did that. Yesterday morning I replaced the plugs with Bosch premium platinum plugs (had great luck with them previously) and soaked the throttle body with Deep Creep after injecting half a can into the motor through a vacuum line. Started it up and it ran just fine. Took it for a ten mile test drive (half of it up a 8% grade at full throttle, climbing the hill like a homesick angel) and it ran perfectly. This morning the wife took it out and it ran like **** again. I have a brother in law who is a SAE certified master mechanic (he knows his stuff in the real world too) and he is out of suggestions. Don't tell me about codes. Either I am going to fix this thing or I am going to set fire to it. And I can't do that because I need it.