Fx4always

Hey everyone new to the forum. Just wondering if you guys could help me diagnose what my problem may be. First off I have a 2012 fx4 ecoboost with 42k and I have been having vibrations in my steering wheel around 60-75mph and then it get worse when I hit the brakes. I have already changed the rotors and it helped for a little bit but the vibrations came back. It feels to be on the drivers side. Just wondering if it could be a defective tie rod end or something with the steering. I had it to two different dealer ships while it was under warranty and they said they could feel it but don't know what it is. They were telling me it was my tires and wheels. I have rotated my tires numerous times and still the same thing. I just need some help!! Thanks