Is this like all of a sudden, or has it been doing it? The reason for that question is, maybe something was recently added to the car and the trouble started. let's say some one put a different set of tires on the rear or front for that matter and the steel belts roll differently, it'll give that kind of motion. Or if you've installed tires that have a direction arrow on them and one or two are not installed properly. The reason I bring it up is I actually did that once.
'95, white convertable, auto trans
, under drive pulley, cai, 3:73 gear. Just enough snap for a 62 year old kid! (my wife's a blond so the top MUST be down, or she won't get in!!)