Transmission will not shift when pulling load
I have a 2002 Ford F-250 2WD with 7.3 Liter powerstroke and automatic transmission. When I pull my camper or have a load behind it it will not shift into overdrive; I have to pump the fuel pedal to get it to shift. I have tried putting a new shift kit in the transmission but this did not help. It shifts fine when not pulling a trailer or load. Any thoughts on what the porblem may be.