i just replaced i beam bushings and uper and lower ball joints and outer tie rods on my f-150 and i still have a shimmy what else could it be

Did you try your pitman arm

yes replaced bushings

this truck has twin I beams and radius arms

I sounds like you changed all the suspension parts. What's left that was not changed? How about wheel balance, defective/worn tire, wheel bearings, shocks?

Pitman arm, idler arm, inner tie tods

Raise the vehicle off the ground. Place on jack stands. Try to wiggle each front tire from left to right being on the lookout for play or klunks. Do the same at top and bottom.If steering components are worn to the point you get a wobble while driving you should see the offending part has play in it.