1994 Chrysler New Yorker Jerks then won't change reverse or

This is our "family" car. We love it. My wife drives it primarily. It has a problem that is worsening. We will be driving along, then all of a sudden it will jerk violently. Then it won;t go into gear until you stop the car and restart it. I immeadiatly thought transmission, but the fluid is full, does not smell burned and is not discolored at al. Also, the oil is full, and all other fluids are as well.
Our engine is nice, clean, and our car has been a nice ride up until now and very comfortable. Could this possibly be a fuel problem or maybe the timing belt?
Well we love our car, can you help us?

The ballard family