GMC Repair: 98 GMC K1500 BACKFIRES, fuel pressure, distributor cap

Question
when i start up my truck and drive it starts bucking and backfires then i will take my foot off the gas and it idles fine as soon as i give it some gas it starts bucking and backfires and sometimes stalls, when it stalls it starts right up just fine, so i am pretty sure its not the fuel pump, i replaced the fuel filter that was not it. It only does it when you give it gas. Please any ideas on what it might be???????  Thanks Bob P.

Answer
Hi
I would recommend a complete tune up, including spark plugs, plug wires, distributor cap and distributor rotor.
After that I would check fuel pressure and injector pulse..
Remember on these trucks with the 5.7 CSFI the fuel pressure is VERY important and a difference of just 1 psi either high or low CAN cause drivability issues.