Fuel Not Burning

[Dominus]

So I took my SVX to my local service station for its annual inspection/emissions test. It pasted the inspection just fine, but not the emissions test. Apparently although the emissions are fine while it is driving, when it is idling it isn't burning up all the fuel and there is some detectable amount left. The mechanic suggested I raise the idle to like 1000 rpms to try and get that fuel to burn and he would reinspect it. So now I guess I need to know how to adjust the idle. He didn't know and also added a comment about not being allowed to or something. Does anyone know how to temporally raise the idle to burn off extra fuel or have another solution?