Just bought a 2001 Cummins, in the morning the transmission is very weird it wont really shift into any gear i can hardly hit 25 mph if I shut the truck off and restart it, the tranny is fine. Is this a bad throttle position sensor? Stuck vavle? Idk..

 

get a code scanner, i could be TPS or if you park your truck on a hill and it sits for awhile all the fluid runs to the back of the trany which would cause it to not shift good right away until its warmed up

 

Im not getting a check engine light though, and i park on a flat surface.

 

ur trans ecm can still have a code without turning on a CEL