It doesn't sound like an engine or drive train problem if it only occurs above a certain speed. Still you should eliminate the posibility. If its drive train related the problem would probably get worse or better depending on engine load (uphill versus downhill, 4th or 5th gear etc.). If you have a standard transmission you can try pushing in the clutch at freeway speed or putting it in neutral and see if the problem is still there.
Most likely the problem is coming from the tires or wheels though. If your wheels have been out of balance and or out of alignment for many years its possible for the tires to wear in such a way that the problem will persist even after balancing and alignment are done. Check to see if your tires have uneven wear patterns. If this is the case try rotating the tires and see if the problem improves, if it does then the tires you were running on the front need to be replaced. By the way, I assume you already had the bushing, ball joints, and tie rod ends checked.
Friday, February 19th, 2010 AT 3:43 PM