My 1994 Caravan sometimes does not want to change gears.

it is going into limp mode. you need to have someone find out why this is happening. turning it off resets the system and works till the fault happens again. get it checked asap before damaging the trans. Roy

Have ignition switch checked for intermittent failure. Maybe check with local dodge dealers parts dept. , they may confirm that , and if they stock the switch that's almost a definite 'yes'.