Why didn't the car idle after cleaning the throttle? I was doing maintenance in 4s and scolded them for cleaning the throttle. After washing, the idle speed is gone.

First of all, make sure there is no idle speed or high idle speed. If there is no idle speed, it must be a fault caused when cleaning you. Ask the 4S shop for professional things, but most importantly, if you have high idle speed, it depends on the brand of your car. Some electronic throttles are different from cable throttles. If equipped with 4S computer, it will automatically reach the original idle speed. I suggest you actually run more 4S shops to give you a clear fault diagnosis. You'd better not tamper with your car, so that you can enjoy the warranty.