My 07 4x4 seems to wander at speeds above 60 going down the highway. It almost feels like there is fluctuation in the power assist. The tire store has balanced the tires and checked the alignment, the dealership has checked the front end and both say there is nothing wrong. Has anybody had the same problem or any ideas. I drive a f-250 work truck with a suspension like a roller skate and its rock solid, I would think this Expo would drive a little better.