Well, my car is surging again. After it is warmed up, it surges between 750 and 900 rpm. The air fuel is going rich to lean with the surges. DONT tell me that the air fuel guage is a lazer light show. I went through everything that had anything to do with the idle and fixed/inspected it. It was fine for a while but is now back. What controlls idle and idle mixture once warmed up? I've tried switching ECUs just to be sure, and it did the same thing. Ideas?