Don-you may have to reset your throttle CV's. It should be relatively easy to do if you have the "book" on your system. I can't imagine what else it could be. You might have to start over with factory defaults but since you don't have a massive collection of locos, it shouldn't take too long. I am sure there are others out here who know the answer, stay tuned.
____________________ It doesn't matter if you win or lose, its' how you rig the game.