Engine idles at 1200-1300 rpm in park when warm. Connected scan tool and the desired idle says 800. Go to the IAC ouput section and manually drop the idle down in 25 rpm increments to 550 rpm but the engine stays at 1200. Next I manually raise the idle speed to about 1600 rpm in 25 rpm increments, and once the tool commands 1200 and higher speeds, the idle does increase and follow the commands. Stop at 1600 at which point I try to drop the idle, but it stays at 1600. If I shut the engine off and turn it back on, it's at 1200 again with the tool commanding 800 rpm. Is this a IAC problem? Like the valve is sticking open. Can it be tested on the bench or cleaned?