Isn't there a PCV valve hook up right around there? it might just be that. If it is leaking that is too much air, causing the Idle issue as well. That is what your codes point to anyhow..
You could always JB weld that. But, sometimes OEM is too expensive.
$52 here :
Engine Valve Cover Camshaft Rocker Cover For Chevrolet Cruze Sonic Aveo 55564395
And the picture confirms the PCV valve location. Make sure it is hooked up.. Might be "free"