Swift 1.5 manual transmission engine idling instability! What's going on ?

If you are talking about the speed of rushing to 2000 after landing, this is normal. When the water temperature is low, that is, when the car is cold, the idle speed will be high, and then slowly fall back to the normal idle speed with the increase of the water temperature.

Also, you said that the speed suddenly shook while waiting for the red light. It should be that the water temperature of your vehicle reaches the temperature when the cooling fan is turned on or off, so that the fan will automatically turn on or off.

When the fan is turned on, due to the increase of coincidence, the speed will fall back, and then the computer will increase the speed to ensure the normal idle speed of the engine. After closing, the natural speed will fall back.