Just finished putting in a wreckers tranny in my 98 dakota 2wd, when I throw it in drive it stumbles a bit... the revs drop pretty low and it almost sounded like a stall at first but then it came back up. I cant test drive right now because i have a brake line i need to fix tommorow when I can get my hands on some line. What are your thoughts on this? It seems to pull fine in reverse and drive for the first few seconds i put it in there before my brakes got to low.

 

Let the ECU learn for a bit before you get worried. Have you checked that battery voltage at idle?