Any dodge ranging from 95 and up have what is called (limp home mode) which is a fail safe mode. this was designed to prevent a throttle failure or unwanted accelleration. What happens is the TPS (throttle position sensor)
gets worn and sends erratic signals and this in turn causes the computer to stop sending a signal to it which results in the transmission shifting safely into second gear .

 

funny though took me talking to 6 different mechanics and doing 6 hours of internet research to figure this out lol

 

I've NEVER heard of the TPS causing this it is normally Speed sensor input/output units on the tranny