I have been having a little trouble with the tranny in my 86 bronco AOD. It works fine and shifts fine until you are going up something steep... and if it roles back any (even a foot are two) then it is like it is neutral. I have to put it in park for 5-10 seconds sometimes 20 and then shift it back into drive before it will go.... any ideas???????

I can drive it all day and go up whatever I want, and everthing works fine with no trouble. but if I have to roll back down to choose another line, then I have to put it in park first before it will go into gear...

I know ford AOD's suck, but might anybody have an idea what it might be, or what would be an easy swap to put in it... I sure don't want to go bad with a furd AOD.