When I drive my eg on the freeway at and over 70 mph I feel all sorts of different vibrations. The one that worries me most is the steering wheel. At high speeds it vibrates pretty hard nad moves slightly from side to side. Also I took it up to 80 to see how bad these would get and the whole car started vibrating really hard. Felt like it was gonna fall apart. I've had this since I bought this thing, and none of my ohter car did/do this sort of thing. What can this be?