Valve Rocker Cover / PCV valve FYI 2009-2011

Bought a Pontiac 2009 G3 it had an off hesitation/cutting out/surging just off idle ever since I got it with 84,000 miles when to had around 102,000 miles it progressed further to include at operational temp to a rhythmic momentary small increase of idle speed about every 20 seconds of about 100 rpm when hot you could here a slight sucking sound seemed from the throttle body and started getting codes forcatalyticconverter inefficiency only when doing short trips around town and restarting the motor after a short stop starting and drive to work it did not do it long drive and let it sit also every since I got the car transmission shifts were somewhat soft 1-2 on 2-3 a little better and on 3-4 it was more positive better and torque converter lock was most positive

did an oil change last week started the motor and warmed it up and adj oil level.

The next morning Had to go somewhere when started made some weird noisy sound popped the hood it sounded like a major vacuum/intake leak took a while to find was not definitely not centered at some area probably coil cover diffused the sound as it was under the coil cover there a small flat area with a vent like 2 or has a divider back side to top and to left a little
plugged it up to drive it and it's not a good idea car ran badly warm and even you could hear preignition/detonation/spark knock after idling a while at a drive through/stop light I figured it was the emissions/PCV valve in the valve cover when I had it hooked up to scanner and watching the fuel trim long term was around 26-30% short term was 20-26% at idle and would drop when driving motor stalled cutting out bad at idle badly and high idle and rpms would not come down if you revved motor in neutral/park had to shut it off

Replaced the valve cover and it included the valve and fixed the problems no more surging and off idle hesitation/misfire/surging when warm actually runs better all over and better throttle response and can feel more positive transmission shifts had a 2008 and that car you could feel every shift believe it been bad a while until total failure.

You can buy the valve separately was doing to do that but did not want to break the valve cover and be stranded.
I going to get one for the old cover and see how that goes probably cut it up first to not damage valve cover.

And that vent does pass a small amount of air depending on vacuum well not really but pressure differentials it's a metered regulator more than valve to let some fresh air in and maintain a constant low pressure in motor crankcase small thing big problem.