to clean the IACV, just take it off and spray brake cleaner on the screen and make sure its clean. The FIAV, is the fast idle air valve, and its the small thing bolted to the bottom of the throttle body with the coolant lines going to it. Take it off, and pull the end cap off, it should have a big plastic nut, sometimes this nut comes unscrewed. screw it back on.

Check out page 172 on the civic helms manual located in the online resources link in this forum