how wide are your tires? my dad has a 97 Impala SS which has 235/45R17s on it at least and, even though that car can out handle most sports cars, it has always had the problem of wanting to track the grooves in the road. now your car shouldn't track nearly as bad because i doesn't have as wide a stance but having the combination of wider tires, worn bushings and steering coupler will definately produce those effects.