My friends SI is not holding a consistant idle. He is ruuning a pretty much stock b16. The CEL is on the i9t is either displaying a 1 or 10. Which he 1 is an oxygen sensor and a 10 is a IAT sensor. He just replaced the O2 sensor today, but the car is running sluggish and when held at a constant rpm, the rpms surge. IAT sensor? bad O2 sensor? IACV?