The throttle of the engine sizzled, but it stopped when the line was unplugged.

Throttle actuator problems, sensor problems, etc. When the cable is unplugged, the engine throttle clangs, and there are problems with the engine throttle actuator, such as motor, driving gear or electronic control unit (ECU) failure, which will lead to clucking, and the failure or abnormal operation of the throttle position sensor and air temperature sensor will also lead to abnormal clucking when the engine is running.