sounds like its running rich for some reason. like whats his name said if theres something wrong with the o2 sensor and its for some reason telling the pcm to add fuel youl bog down untill you get to higher rpm. check for intake leaks? if you have a leak the pcm will read lean and try to compensate by adding fuel. have you done any repairs or had anything apart right before this started happening? suck it up and pay an hour labor for someone to hook it up to a scanner, at least get a code or soemthing so you can start somewhere.

 

haha yea i prob will go pull it off tonight anyways....ive had it off before and it isnt that loud...atleast compared to my 86 chevy 350 with dual bullet type magnaflows lol. Im also buying a code reader tommorow so i dont have to go to a gm dealer for this stuff.

 

Hmm i havent had anything apart or nothing...ill take a look for leaks tonight also because it deff feels like the gas is getting dumped in causing sputtering issues.

 

Might as well get a fuel pump on the way. My 2000 GMC Sierra 5.3L is doing the EXACT same thing and then I measured the fuel pressure and it is all over the place. Mine will be here on Friday. Good Luck.

BTW, I hope you learded the same thing as I did, NEVER let these trucks get below 1/4 tank and change the filter every 20,000 miles.

 

New plugs / wires and fuel filter first. Cheap R&R and probably needs it anyway.

 

Never did let the truck get below half a tank and the old guy i got it from said he never either....i still havent figured it out but its getting worse now at high rpms in second gear (5000rpms) it cracks and pops and stuff.... sounds like out the intake.....yikes. I will be pulling all the plugs and checking the wires etc this weekend but the fuel filter was changed right after i got the truck which was less than a year ago. If the fuel pressure isnt jumpy and the wires and plugs all check i guess its time for a stealership to look at it. Oh yea i also have no codes showing with the scanner so thats out also.

 

Check your fuel pressure regulator. Its pretty easy to rule that out. I would replace plugs, wires and fuel filter also.