-3 pedal auto-shift-. The truck runs fine until it gets around 55mph and has to shift from 9th into 10th. At that point it starts to loose power, sputter and stall out or down shift into 2nd. It then stays in 2nd until you turn it off. I have had the J-1939 replaced(transmission wire harness). Could it be batteries, ECM, fuel pump/pressure..?