2015 Lexus IS STEERING,ELECTRICAL SYSTEM,UNKNOWN OR OTHER

When driving at high speeds on the highway (75-85mph) after about 20 mins or so, the steering wheel feels like it locks up or gets stuck. The only way to get it back to normal is to jerk the wheel a bit resulting in swerving. This happens almost everytime I travel across the state. The car has passed all inspections at the Lexus Dealer. This past visit to the dealership, the tie rod was found to be corroded, however the technician does not believe that is the issue. We believe it is the steering rack. This car has not been in any major accidents and was having this safety issue prior to a slight fender bender. The issue is a huge safety concern because the steering wheel "stops respondings" and needs to be jerked or swerved to go back to normal.