I have a 1999 dodge Dakota 3.9L 4x2 with a 42re transmission and when driving for alittle while it will kick out of overdrive and turn the o/d off light on the transmission temp light doesn't come on just the o/d off light and you can not turn it back on with the button on the gear selector and as your driving it the o/d off light will go out and then it's fine for awhile and then will do it again but I don't have any issues with the rpm bouncing around like I've read in some of the forums but would definitely like to figure out what's wrong with it before something expensive happens any ideas?