my 1998 Grand Caravan Slows Down And Stops After I Drive For About 30 Min.the Engines Never Cuts Off And The Brakes Are Good, What Could Be Causing This To Happen. It Has 60,000 Miles. It Will Move After It Cools Off

You didn't give us much to go on.
My Caravan slows down and stops too when I put on the brake and the engine doesn't cut off. We need more info.
When your Caravan slows down, what are you doing, pushing the throttle to the floor, letting up, putting on the brake, what?
What is the engine doing, is it losing power, revving, backfiring, surging, what?
What is the transmission doing?
Is there any unusuall noises associated with the problem. Are the guages showing everything OK, is your check engine light on?