Passat b5 1.8t engine is very shocking. Why?

This fault phenomenon is related to the quality of the oil added and the carbon deposition in the throttle body. First look at the throttle volume. If there is carbon deposit, clean it up first, and then observe it in trial operation. If there is no carbon deposit, it is suggested to choose a regular gas station when refueling, or it may be the jitter caused by adding inferior gasoline. The second is to look at the spark plug. The spark plug should be replaced every 30,000 kilometers, and it should be replaced in time when driving to the specified mileage.