tranny trouble
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.