WE HAVE A 1994 FORD F150 4X4 THAT HAS A PROBLEM THAT NO ONE CAN SEEM TO FIGUIRE OUT. AFTER THE TRUCK IS DRIVEN 2 OR MORE HOURS STRAIGHT, IT STARTS TO DOWNSHIFT AND WE DON’T KNOW WHY. IS IT A TRANSMISSION PROBLEM OR IS IT A SENSOR? IANY IDEAS? IT DOESN’T DO IT EVERYTIME, IT’S VERY SPARATIC.