My car often shakes when I’m on the freeway in a pattern, then stops. Unless I’m using cruise control, then it doesn’t happen at all. What could this be?
Most common reason would be the tires. They can be out of balance or have a busted belt. See if you feel it more in the steering wheel or in the seat. Then rotate the tires front to back and test. If it moves then you know for certain it is in the tires.