I just bought this vehicle 2 days ago about 40 miles away from my place everything worked ok driving it home. but yesterday someone thought it needed more trannyfluid without brining it up to operating tempature. so today it drove fine for about 15 miles then the overdrive started slipping then next the drive but 1st and 2nd still worked. so i drained some fluid out till it was nice and hot and showed full then both drive and overdrive started working again, but then went out a few minutes later . well I had already bought everything for a tune up including the tranny it seems to be working itself out. but i'm still going to give it a change with fluids and filter but if that don;t help what should i look at next?