Why did KIA k4 run a red light and hang N gear, and the idle speed rose to 2000 rpm?

Hello, as you said, when you were in D gear, the speed was 2000 rpm. This situation belongs to high idle speed, because your car will not reach 2000 rpm when it is in D gear, but when it is in N gear, the speed will return to 2000 rpm, which is obviously high. If your car is an electronic throttle, I suggest you clean the throttle. If your car is a cable throttle, I suggest you check the cable of the throttle and check the idle speed control slide valve. I'm glad to answer your question. Have a nice trip. If there is something wrong with your car, ask the car mechanic. 4S shop professional technician, 10 minutes to solve.