A while back I had a problem with my 94 AWD. The transmission would down shift real hard at high speed when I let off the gas. I spent over $1600 dollars, many trips to different shops (the last was a ford dealer) attempting to get this fixed without success. Finally I took matters into my own hands. Looking at the transfer case I noticed two pick-up sensors. Not really knowing what they were, but willing to try anything at that point, I took them out. They looked the same so I switched them around. I tried to drive the van, but couldn't, it felt like the driveshaft had fallen out. I then went to another ford dealership to order two new parts. That's when I learned they were range sensors. They cost $80 each and since I replaced them I've had no more problems. I was very upset that a transmission shop's and a ford dealership's (so called mechanics) couldn't figure this one out.