Steering Wheel Vibrate problems of the 2009 Dodge Ram 1500

This vehicle was bought used at a certified dealership, could not drive a fast speed for testing do to traffic and weather conditions. Upon driving the vehicle home noticed excessive vibration (rear end shakes and front end shakes) on turns on the highway at various speeds from 60 to 70 and even at 80 steering wheel shakes as much as the vehicle did. My wife and I thought it was tires being out of balanced. We got new tires and life time balance thinking it would fix the problem, but it did not. Vibrations comes and goes but mainly comes on when making turns on highway either left turns or right turns. Notice a lost of control when hitting even a little bump at high speeds as well. We then received the recall letter for the retaining nut on the rear end to be replaced. I would think this is related and may be it would fix the vibration problem, but it did not, vibrations are still there at high speeds. Even brought it back to have the tires re-balanced but problem still exist. This is on a 2009 Dodge Ram 1500 laramie quad cab. I don't know if this pertains to the recalls or am I eligible for the buy back programs. We have put too much money into it and problem still exist and no one knows what the cause is.