Driving highway speed, after hitting rough area, front end starts to shake violently causing almost loss of control. took to ford dealer in laredo, tx and was repaired. this lasted about 8 months and problem arose again as i was driving the interstate in ms. took to local repair and had king pin[?] replaced but didn't stop the problem. checked tire pressure, shocks, wheel bearings...research has proven this is very common problem but no real answer. this truck is dangerous to drive and cost over $50,000. what do i do now? *tr