HELP! I have a 93 Grand Caravan with 208234 miles. It's been a great van, but sometimes when slowing, the transmission (4speed auto) will drop back into a low gear and stay there no matter what speed I go until I put the vehicle in neutral, turn the ignition off and then restart. Sometimes it goes back to normal and sometimes I have to pull off the road and wait a few minutes. The transmission feels tight the rest of the time. I have replaced the input and output sensors. The transmission was rebuilt about 60k ago. I have heard of this happening to other Dodge drivers, but don't have a clue where to start.

 

I would get the codes pulled, and then I would look into the solenoid pack as the source of trouble. I had this with my 91 GC. When the tranny was rebuilt they may not have changed the solenoid pack and the tiny mesh screens can get plugged with metal. If it was not changed the metal from normal wear n tear may have built up enough to cause this. When you turn it off , the system pressure drops and enough falls away from the screens for the normal solenoid pressures to be present at startup. The solenoid pack is right on the front of the tranny and held in place by 1 (8mm or 10mm) bolt and an electrical connector.
If the pack was indeed changed when the tranny was rebuilt, then this might be a sign of impending doom. Good Luck