I feel the car shaking during the warranty period. The 4s shop said that there is a charge for cleaning the engine and throttle and doing dynamic balance. It's Cadillac, 35000

I feel the car shaking during the warranty period. The 4s shop said that there is a charge for cleaning the engine and throttle and doing dynamic balance. Free during the warranty period;

Cause of throttle failure; The spark plug and throttle are too dirty or there is too much carbon deposit in the nozzle, and the gear starts to shake, and the three-way catalytic temperature is not enough, so the carbon deposit in the engine seriously causes the car to shake. Because the gasoline adsorbed on the carbon deposit after landing is sucked into the cylinder of the engine for combustion, the combustible mixture of the engine is sometimes rare and thick, which leads to idling jitter after cold start. Solution: The company cleans the oil circuit, and checks whether the idle motor has carbon deposit, so it should be cleaned.