Cory Martel

before we get to the fun stuff heres the story , i have a 2007.5 5.3 silverado ,500,000 miles ____ the past 3 years its ran fine with its little mods and with out adding or changing anything , i drive about 110,000 miles a year , oil changes every weekish , yea no ****** , i also tow heavy daily , like twice the gvwr and sometimes even more lol but everything has always been fine and then ****** started getting weird , repetitive misfires and backfires COMPLETELY random though and im unable to replicate it , well it hapopens more under load and sometimes during idle , happens consistently . so did a few tests and couldnt find anything contributing to the misses . NO CODES besides traction control , and abs ( abs light is for rear wheel speed sensor) btw random misfires are on all 8 cylinders , not at the same time though oddly the first time i changed the o2 sensors it ran great for 30 minutes and then started doing the same ****** again so ive changed them 3 times so far this month , same part number , denso i believe im only running headers , straight pipe and cold air intake afm is tuned out took it to 3 reputable shops and they all gave up within days . so heres what i did : 5.3 reman from autozone , lh6 same as old block new plugs new wires new intake manifold and gasket new oil pressure sensor new iat sensor new mass air flow sensor 2 new upstream o2 sensors new crank shaft sesnor new cam shaft sensor did a crank relearn but was also worried about doing that considering it was still running like ****** and i didnt want the (relearn) to think thats how it "should" run new ecm ran through harness and replaced ecm grounds new fuel pump added chassis/bod/engine grounds ( extra grounds everywhere ) checked injectors , all firing checked coils , all firing added reducer to straight pipe to add back pressure just to clear up a theory and guess what , nothing has changed checked fscm , (fuel system control module ) all good and even bypassed the fscm just for ****** to see if it would make a difference and it didnt went thru the chassis harness to check for shorts , nothing damn near out of money now , out of options too , i feel defeated . and my wife thinks i hate her because i stay tinkering with this god damn truck all day lmao I NEEED HELP