Thanks for all of the great responses, the problem does not happen when I brake, just when I'm going down the road. That's why I cannot tie it to an event like braking or going over a pot hole. Also, braking is smooth so rotors are not warped. If the problem were unbalanced tires, it would do it constantly or at a certain speed and not just at random. I think that it has to due with a worn suspension component(s) such as tie rods, bushings or ball joints.

Thanks,
Chas