i have a 93 taurus that would downshift for no reason... drive along at about 35 mph and all of a sudden it was like someone put it into first gear for a second or two and then drive along fine.. it was the vehicle speed sensor.. the wires to it were damaged when i changed out the motor mounts and jacking up the engine stretched the wires and made the copper inside the plastic/rubber coating break... eventually i had to drive home one day at 5 mph. as it would not shift out of first gear.... a fix on the wires solved the problem.. this might be your problem???????
if so its alot cheaper than trans. problems....
