It would be worth giving the iscv a spray with carb cleaner then furniture polish containing silicone afterwards.
Things that can raise the idle speed include the CTS if engine thinks it's cold, so could check CO.
The engine relies on air, so try adjusting when hot and electrical loads turned off, the bypass screw on the throttle housing underside, if this doesn't have the desired effect, then I would look for air leaks.
tabetha