Need to replace / clean Idle Control Valve?

Hi All,
I've had my MK3 2Litre 8V 1996 for a year and its been great!
Then suddenly its begun dropping revs when sat at lights, slowing down for corners and at junctions.

Am I right in thinking the ICV is connected to the throttle body and I would need to replce both if I want a new one?
Also is it possible to clean it as I know a friend had a similar issue and his was caked in grime?

Where am I looking and whats the best way of approaching this? Am short of cash at the mo but want to give it to my wife as shes wanting a run around :)

Cheers for any feedback in advance.

-Rich