What should I do if the famous cool car engine starts to shake obviously?

As for your question, since you haven't seen the existing car, the main cause of the failure should be carbon deposition on the accelerator and carbon deposition on the air intake. When the car is cold, it will absorb some gasoline, which will lead to the mixture being too thin when the engine is idling, which will lead to unstable idling. So you should check whether there is too much carbon in the throttle and air intake. If there is too much carbon deposit, the cross-sectional area of the air passage will change, which will make the control unit unable to accurately control the idle intake, resulting in too lean mixture and abnormal combustion. It is recommended that you clean the throttle and the carbon deposit in the engine intake and combustion chamber. If there is too much carbon deposit, you can choose the method of hanging bottles.