The throttle is broken. What's wrong with cars?

The car with bad throttle has the following faults: 1, the engine idle speed is unstable, the high idle speed does not continue to drop, and it is difficult to start the engine, especially the cold start. 2. Engine idle speed is unstable or there is no idle speed. 3. The engine is difficult to start. 4. The engine has insufficient power, poor acceleration performance and unstable operation. 5. The exhaust pipe of the car emits black smoke to improve fuel consumption.