I need help!

[zhopkin17]

I have had my 1988 Ranger for several years now. It's a 4x4 with a 2.9L and an automatic on the floor. Recently it has developed a rather signifigant problem. When I shift it into overdrive I've got NOTHING! The tranny will just whir. If I put it in other gears I still have nothing, and I will continue to have nothing until I put it in park shut the engine off and let it sit for a while could be a few seconds could be a few minutes. Then I can start it and as long as I never pause in the overdrive slot It will move and shift smoothly through all the gears except overdrive, it's like it's not even there. I've changed fluid and changed the filter found absolutely no metal shavings what so ever. The fluid did appear burnt, but didn't have a burnt smell. Have any of you ever ran into anything like this or have some insight into the matter?

 

[adsm08]

I'm thinking the valve body may have crapped out. That is a total WAG, but I honestly can't think of anything else that even has the potential to do something like that.