What if Jetta restarts breathing for a while?

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 adsorb some gasoline, which will lead to the mixture being too thin when the engine is idling, which will lead to the unstable idling of the car. 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, abnormal combustion and unstable engine idle speed. The pressure in the fuel system is also low. I hope my answer is helpful to you.