If it's any consolation, I've been facing a similar situation for over a year. I feel my vibration mainly at speeds of 50+. However, with mine, the vibration isn't consistent. Most of the time I have vibration, but occasionally it is smooth as can be. I've replaced tires, rotated tires, switched tires from one car to another, balanced tires, new brake rotors, four new motor mounts, four struts, two ball joints, two new (rebuilt) drive axle assemblies, and a driver's side sway bar end link. The tie-rods seem to be fine, but maybe I'm overlooking something. The only other thing I can think of is control arms, or a 4 wheel alignment, although the tires are wearing normally, and the car drives and handles fine. Don't know.
