so every time, EVERY time the car is at operating temperature, the CEL comes on and it starts to run like poop. the code is 1221 which is the oxygen sensor code. I don't get why it comes on only at idle. the sensor is new and where its suppose to be. the car will eventually get better and the light will go off but it'll do the same thing if it sits for 3 mins at a stop. give me some suggestions people! i've checked just about everything so opinions are welcome.