what would cause a high speed vibration/shimmy from the front of the vehicle?

What is your question?

Vibration in steering wheel at 70 mph and up. Replaced all 4 tires, brake pads and rotors, front end appears tight. Ball joints okay, tie rods okay. Stabilizer rods okay, Tires all new. Rotated tires and vibration/shimmy still present in front. No play in steering rack. Just can't figure out what is causing this problem.