Ive got a 91 f150 4wd. Have rebuilt most of the front end...tierods...ball joints. Still have an issue. If truck has been driven forward amd stopped wheels sit bottom in top out. If the truck is backed up amd stopped it sits the opposite tires bottom out top in. Ideas on what to replace next ro stopp the movement

 

That's generally what happens with the ford TTB front end. Though it should not be super obvious if it is aligned properly.

 

How's the axle pivot bushings?

 

this, and also the radius arm bushings?