Idles to fast in gear

My father bought a 2011 Aveo new and has said it idles to high since the day he brought it home...it has the eco-tech engine with a standard shift...he brought it up my drive (15% grade for about 150 yards) the other day and never touched the throttle...it idled up my drive at 1000 rpm then at the top he pushed the clutch and it went straight to 800 rpm...why does it do this...anyone else have this happen? Thanks for your time

I get the Idle control valve is not working correctly. Maybe a clean followed by a replacement.

How would you go about cleaning the idle control valve?... by removing the throttle body. Then what?