On my 2000 2500 4x4 automatic with 120,000 miles the trans has started to act differently. It starts out in the cold very slowly and also when its warm. Like it's in second gear and it also hesitates or feel like it's bucking. If a put the shifter in first it moves fine. I read this could be the governor pressure sensor. Does anybody have any advise where to start. And a part number.