Braking problems

When I come to a stop from higher (above about 30 MPH), my car shakes as if the front rotors were warped. Since it doesn't seem to happen at lower speeds, I'm starting to question the control arm bushings (or something like that). I guess my first question would be what type of bushings are on the car, and how likely is a 1996 LSi with 60K miles to have worn bushings? The rotors were replaced by the previous owner, but I'm not sure how/when/where/etc. There does not seem to be much wear on the rotors, but having seen other posts and it doesn't look like wear has much to do with anything. Does anyone have any suggestions? Thanks.

Clarke Russell