backfiring.
carb or timing
You either removed the catalytic converter or you are running too rich.
your timing is off or bad camshaft.plus starving for fuel....
123 hp
This is called backfiring and can be due to a variety of causes, such as incorrect air and fuel mixture or a faulty ignition.
Roughly 112 horsepower
10w40 full synthetic.
Well, mostly the fact that its extremely heavy and not even close to being aero-dynamic.
Could be a hole or leak at one of the joints or cylinder head bolts / nuts.
Your GMC truck may be backfiring due to several issues, such as a faulty ignition system, incorrect timing, or a rich air-fuel mixture. Other potential causes include a malfunctioning fuel injector or exhaust leaks. It's important to diagnose the problem accurately, as backfiring can lead to further engine damage if not addressed. Consulting a mechanic for a thorough inspection is recommended.
it is mostly the timing off or the carburater needs adjusted.or the petrol filter requires replacing [at fuel pump]