Balancing would be the first thing I would try, when your car hit the metal it coulda knocked a wheel weight off. Re balancing usually isn't too much, and its something that you cant do yourself.
Was just going to suggest this.
Make sure your wheelweights are still there...
2001 Grand Prix GT Coupe
Comp G Wheels - SS Corners - Infinity Sound - Tint - Digital DIC Swap - 893 Fogs