So this has happened twice in the last 2-3 months. At complete random, the steering wheel would violently shake. I mean VIOLENT. I’m talking full 1-2 inches of shaking left and right (not like a tire out of balance shake - more violent). In addition, there is a hard thumping sensation under the seat and it feels and sounds almost as if there’s a massive rock stuck in the grove of one of the tires. Both times I pull over, put the car in park, do a visual inspection, see nothing, and drive again. For unknown reasons when I put the car in park and start driving again, it goes away. There’s absolutely no predicting when it happens. Completely random. Both times were at highway speeds. I’m at a loss.