My 1995 F-150, 5.0L, Automatic Transmission, 4x4 Extended Cab with 110k miles has recently experienced occasional transmission slippage in O/D going approximately 40 mph plus. It seems to happen more frequently at speeds of 60 mph or greater. I have switched the O/D off when traveling at slower speeds to see if it would slip and it did it one time. The transmission fluid is at proper level and looks good in color and has no burnt smell. Has anyone out there had previous experience with this problem or knows what the problem might be?

 

It's most likely a bad transmission range sensor. That's the part on the driver's side of the trans with the wiring harness attached. Replace it.