I've been having this problem with my 98gt for a while now, but nobody yet has been able to tell me the problem. The steering wheel and pedals seem to vibrate whenever I hit around 55-65 mph. (Either accelerating, cruising, or slowing down to that speed.) I have had the car re-balanced a total of 5 times in the last week, both by BigO and Ford. With each balance it has improved (mainly because Ford did a much better job than BigO), but I still have the problem, and can't figure out how to solve it. The bearings and rotors were checked and were fine. Could it be my wheels? (I have 17x9 Eagle alloys) or the Eibach pro kit springs? Any other ideas? Ford seems to be stumped.