I have a 1994 dodge ram 2500 w/cummins and 4x4.
While driving at highway speed if I hit a bump in the road the truck shifts down increasing the rpm of the motor by about 200. The bump only needs to small like a expansion joint in a bridge.(point being it doesn't take much to make it shift). I first thought it might be dropping out of overdrive, but after reading a bit could it be the torque converter clutch kicking out?

I think I have solved the problem. I disconected the two batteries, cleaned the electrical connectors to the transmission and plugeed everything back in. I reconnected the batteries and everything seems fine.