2011 LEXUS GX460 Steering Problems

VEHICLE DRIVES FINE AT LOW SPEEDS. AT HIGHWAY SPEED 65 MPH AND UP STEERING WHEEL FEELS LIKE TRYING TO MOVE A SPINNING GYRO. THE VEHICLE WANTS TO CONTINUE IN THE DIRECTION IT IS GOING. REQUIRES BOTH HANDS TO MAKE SMALL CORRECTIONS IMPOSSIBLE TO DRIVE WITH ONE HAND. HAD LEXUS INVESTIGATE PROBLEM THEY RECENTLY GAVE UP. THIS VEHICLE HAS HAD THE PROBLEM SINCE IT WAS NEW. I HAVE DRIVEN OTHER GX460 VEHICLES WITHOUT THIS PROBLEM. VEHICLE NOW HAS 28,000 MILES STILL SAME PROBLEM. WE STOPPED DRIVING THIS VEHICLE ON THE HIGHWAY. WE ONLY USE THIS VEHICLE AROUND TOWN WORKS OK AT LOW SPEEDS. *TR