1999 Silverado Problem

The problem vehicle is a 1999 Chevrolet Silverado 2500 4x4 6.0L. It starts right up, but when you try and pull away, it has no power, backfires through the intake, and won't go over 5 MPH; all of a sudden it will straighten itself out, and run, with a small hesitation even when warmed up. Already installed new GM Fuel Pump, Fuel Pressure Regulator, TPS, spark plugs, and fuel filter.

There are no computer trouble codes registered.

mass air flow ? possibly

We have cleaned the MAF and the TB, but it didn't solve the problem.

cleaning my MAF did not help i had to replace mine but that was in a ford and it was 380 dollars

Was your problem similar to this?

mine was if i gave it any more gas than about 1200 rpms then it was loss of about 3/4 of the power to the truck. and it DRANK gas like crazy

I had a car do that to me once and it was a badly worn out exhaust rocker arm..... you did not mention how many miles/kilometers you had on it....... possibly a sticky valve........ once the engine warms up a bit it frees it self up...... just a thought...

I had a car do that to me once and it was a badly worn out exhaust rocker arm..... you did not mention how many miles/kilometers you had on it....... possibly a sticky valve........ once the engine warms up a bit it frees it self up...... just a thought...
Intake... internal vacume leak?

I had a car do that to me once and it was a badly worn out exhaust rocker arm..... you did not mention how many miles/kilometers you had on it....... possibly a sticky valve........ once the engine warms up a bit it frees it self up...... just a thought...
Intake... internal vacume leak? is it using any oil?

there is a service bullent on that check with you dealer it has to do with a relearn on you crank sensor you need to be reprogammed......tommie99

i have a 99 2500 crew with 5.7,engine seems to run right until you put it next to another then you can here a slight miss has new plugs wires rotor & cap but still a hesitation .the hesitation gets real bad at full throttle from an idle i have no cat's and my scanner reads intermittent 02 sensor codes sometimes one side then the other as well a knock sensor code gm tech said it has a lean misfire feul pressure is good and regulator is new i suspect injector poppets any suggestions?i also tried a maf and a tps off of a buddies truck truck that runs good no diff.if i unplug the o2 sensors it should run rich and solve the problem right so i tried this no diff. diagnossis time is costly.

check your TPS sensor, its one of those sensors that the engine idles fine w/o but if you try to push on the gas and the sensors bad it will stumble like a mofo.

My buddies' '99 had similar problems and he replaced the fuel pressure regulator. It now starts every time, runs better at start-up and he says drives better. We removed the vacuum line to see if fuel was present. Fuel dripped from the line, proof that the regulator was leaking and bad.
There is a thread on this forum regarding regulators.