Yeah post back if you figure out what it is. I know what you mean in your description of it feeling like the wind is blowing the car back and forth at highway speeds of 70+ MPH. It is almost like the car is in small ruts and it is having a train effect. If you have ever seen under a train when it is moving it moves back and forth just a little from flange to flange. A guy at work told me it could be the fact that alot of semi trucks travel the highway and grove out the surface of the road making a small depression where the wheels are traveling. I have good ball joints, tie rod ends are new, and the sway bar is a new GMPP sway bar. I recently found out my lower control arm front bushing has seperated, but I dont think that is it. That just causes a clunk when turning right sometimes. I am thinking it has something to do with the steering gear
