Last year I took my car into the dealer with a rough idle. They said that the injectors were dirty and weren't allowing enough fuel to get into the cylinders at idle, so what they did is they cranked up my CO setting so "more fuel could get into the motor at idle" and supposedly cure my problem. Well after being a regular visitor to this forum for a few months now, I have seen the rough idle issue come up quite a bit and never once have I heard of someone else doing this or recommending this. So I am thinkin the dealer was full of it.

By the way, my rough idle did not get better, actually worse at times...AND I obviously get worse gas mileage.
So my questions: how can I figure out or does anyone know what my CO was set to from the factory (euro car, so it might be different?), can I do this myself? and where is the dial? Thanks for any help!