What causes unstable idle speed, shaking, and automatic stalling in the Volkswagen Santana?

[AidenFitz]

The reasons for unstable idle speed, shaking, and stalling may include: Severe engine carbon buildup: A very common cause of car shaking is a dirty throttle body or excessive carbon deposits in the fuel injectors. The solution is to clean the fuel system and check whether the idle speed motor has carbon buildup, which should be cleaned if necessary; Ignition system issues: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance in the ignition system can also lead to such fault symptoms. Inspect whether the spark plugs have excessive carbon buildup and replace them if needed; Unstable fuel pressure: If you have already cleaned the engine carbon deposits, cleaned the throttle body, replaced the fuel pads and spark plugs, but still notice shaking at idle, it is recommended to visit a 4S shop to check the fuel supply pressure and the intake pressure sensor for normal operation. If the fuel pump's supply pressure is abnormal or the intake pressure sensor values are incorrect or malfunctioning, these can cause the car to shake. Check the fuel pressure and replace components if necessary.