I have a 97 F150 4.2 v6 automatic, about 140,000 miles. When I shift into reverse it has no power, it kind of shimmys, and shakes. The other gear work okay it's just in reverse that's giving me fits. I checked the fluid still red and no burnt smell. I did notice some leaking going on but it doesn't leave a puddle, it's basically on the area around the transmission. Fluid level is still good. Recently it has slipped on occasion, and about 6 weeks ago I replaced the egr feedback sensor it seemed to help but I still had slipping issues from time to time.

 

Slipping in reverse is probably a bad thing. I would suspect damage or excessive wear on the reverse clutches or the reverse band.

Darrin