Well, I'm not going to read the other post, but personally, I would start with looking at the steering components (i.e. inner/outer tie rod ends) and ball joints.
You said you replaced the calipers, did you grease the slide pins well?
What about alignment?
Maybe the subframe is moving?
What about it actually being something in the rear suspension (i.e. toe adjustment arms, control arms, bushings for either)?
