Idle speed switch

I need your help. I in process of trying to fix my girlfriend 1995 audi cabriolet. It idles with a slight stumble and I can feel in when I drive. The engine light comes on when driving. I got a code reader and the come comes out to be "idle speed switch - f60 does not close / open circuit.

My question is were is the idle speed switch located? I don't have a manual for the car, so can someone post or send a pic for me? Can the switch be cleaned or does it have to be replaced?

Thanks, Cory
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