I got a 1994 gmc 1500 4x4 with a 350 auto. The tranny loses overdrive and third gear after about 30 mins of driving it i will have first, second and reverse, but if i let it sit for about 15 mins it will shift through all the gears smoothly and i can go for about anther 30 mins befor it acts up again, the fluid is clean a up to the line. some guys say the tranny is dun and others say it could be a senser, any kind of help would be great.
have you checked the transmission fluid level "full" with the engine running in neutral...if so was the color cherry red yet? did it smell burnt?
have you had throttle position sensor ( TPS) looked at? I know on some vehicles the tranny gets a signal from the TPS.you might take it to a tranny shop and have the TPS checked out,its worth a try.......bigc52
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