This may b in the right direction - or not...
Well, now that your truck is getting a few years on it, you will be discovering some of the wonderful Dodge accessories. This particular one tends to be from corroded contacts on the switches themselves. I've replaced all but one of mine (on my classic '94 the window and door switches are the same) and that last one is now on the list.
I don't know why they tend to be suceptable to oxidation but mine are. If you don't have the "express down" window switch, your window and door lock switches may be identical like mine. You could try swapping them to confirm my theory.