Engine/Transmission (1998.5 - 2002) Auto Transmission shifting difficulty??

[Gonzo 1066]

Drove a friends 99 Dodge Cummins auto the other day. It shifts very firmly and crisp 1st and 2nd. It then hesitates or refuses to shift into 3rd unless you let off the throttle. Most of the time it shifts normally when it is warmed up there is 127000 miles on the original transmission. I thought the Throttle position sensor or a sticky valve? It does have a BD auto command unit on it. Any ideas out there?

 

[outlawram]

Thats what mine was doing when my transmission went out. But it did it when it was warmed up and when it was cold.