Alright, I have a 2002 Chevy Silverado 1500 4wd with the 5.3. My issue is that when I TRY to accelerate, the engine stumbles and bogs and backfires and does this til I hit about 60 mph, then runs a lot better but backfires and pops. I do not have the cats installed because I replaced the exhaust with a 3" head back system. No downstream O2 sensors installed( been that way for over a year) Fuel pump has been replaced and fuel pressure is where is suppose to be. Fuel filter has been replaced. Getting the normal p0300 code of course. I've swapped out tps, iac, idle control valve. Guess I need to just replace those instead. Any ideas?

 

Missing under load, as you describe, is characteristic of secondary ignition problems (coils, wires, plugs).

If you’re unsure of when the plugs and wires were last changed, I’d recommend replacing them.

The ground circuit for the coils is known to have problems. It attaches to the back of the engine block near the oil pressure sensor. Remove it, replace the eyelet, and clean the block contact area with emery cloth or equivalent to get clean metal, then reinstall the eyelet.

You can also try pulling the crankshaft position sensor and inspecting it for scratches on the cap. If scratches are present, replace it and put at least one shim (included with new sensor) on the sensor.

 

Thank you for the advice. Your recommendation is the first time I've heard that could be an issue as I have already tried everything else I've previously read. I will let you know if that solves my issue