i have a 1987 chevy suburban 5.7L 350 and it is starting and runs for a few

[alex]

seconds and then the rpms? start to fluctuate alot and occasionally it will die. i have replaced the spark plugs, spark plug wires, distributor cap and rotor, and the fuel filter. it seems to run smooth a little longer but then starts to fluctuate. i have a feeling it might be the fuel pump but am not sure how to test cuz its in the tank and dont want to drop the tank if i dont have to. can anyone help

 

[hammerdown]

ck. your pvc valve may be stoped up sounds like a fuel problem to me! maybe water are bad gas!

 

[Mark]

Does it rev really high? If so check for a vacuum leak(intake or what ever). But if it idles fine cold but not when hot, it may be the EGR valve. Do you have any codes?