What seems to be the problem. Mine at the moment is fine on smooth surfaces but as soon as i hit bumps and all the other crap on the roads i get a real bad vibration in the steering wheel, i thoughht it was my bushes but it turns out my struts and shocks are stuffed beyond repair, my swaybar links are bent and my steering rack needs an overhaul + a few other little things.
I'd take it to a steering and suspension specialist and pay the $20-$30 they ask to do an inspection, that way you know for sure whats wrong.