I had that kinda feeling when I first got my GT..it had the stock suspension and was a little un-nerving at about 80 or 90 MPH..
I had Tokico non-adjustable shocks and Eibach prokit springs installed and the stability was greatly improved....It felt less bouncy and "swooshy" (if you will
),a much more confident feel.....Of course the set-up and feel and trying to go for would probably not be the best for the track but,that's something thats more up to you and what you want to do with the car...-Milt