I have a 1998 Dodge b3500 van with 146k miles. When I first start it in the morning and put it in gear, it is slow to move, like it's slipping. But once you start going it drives fine, but if you come to a stop and start again, it down-shifts hard. If I put it in low gear and start from a stop, then manually shift up it works fine. Someone suggested it might be a shift module, but I couldn't find one on the transmission. Please help.

 

I'd start with doing a fluid/filter change and adjusting both bands.