99 yukon 350 vortec loss of power?

when floored to pass or just kicking into low gear, engine races but not the rest. don’t think it’s tranny. Disconnected MAS sensor and it went like a bat of hell. sadly, that was short lived. bought MAS cleaner and made very slight difference. HELP

Does the check engine light come on?

The MAF sensor can be tested. Don’t just throw parts at it.

fuel injector cleaner.if you’ve been eking out all the mileage you can get, you have crap all over the injectors. or the clutch discs have gone south.

thanks for the advice. my mechanic said he will check it out.

been running 3 tanks of premium fuel and have tried injector cleaner. any suggestions on a “good” brand name??? thank you.

any brand should work. the RPM’s rise, but doesnt go any faster, is that correct? how about your buddy, RPM’s go up but no speed?

you could have a weak spark or low fuel pressure.