As soon as the car started, the speed reached 4000-5000. I didn't step on anything at this speed. I was angry when I set fire to it. What happened?

Usually, if the idle speed is abnormal, the method is to clean the vacuum tube of the throttle idle valve and the air pressure sensor (note that the throttle needs to be initialized after cleaning the throttle). Your situation may be caused by dirty throttle and inaccurate throttle position sensor when collecting oil and returning to idle speed. Suggestion: Clean the throttle valve and idle stepper motor. If not, use a diagnostic instrument to measure the data flow. Should the throttle sensor or throttle be replaced? Don't try to brush ECU.