I've been having this problem with starting from a dead stop it moves very sluggish until 5mph, then it gains no more speed and the revs continue to build until 3grand. then it shifts into 2nd rough but then its fine until i drop back to 1st. Today I reset my ecu and let it run for a minute then ran it around town for 15 min. and it seems fine. What could have caused this?

 

Auto I'm assuming? Could be a bad seal, clutches, or a band. Eihter way, it sounds like a rebuild time. If your lucky its just a bad solenoid.