I had decent success with the Aluminum Valve Cover for my N14 but the burrs and quality is definitely much to be desired. I would gladly pay $400 for a really decent cover...I am not paying $1200-2000 though. think the cover for the PCV diaphragm wasnt sitting how it should have been on mine, after replacing it with a stock diaphragm/cover the idle stopped dropping and now idles smoothly. I will set up a camera to watch the exhaust for smoke, if it continues I will buy a new original valve cover. I just purchased an evap smoke machine too...will be great for more diagnostics.

If it does turn out to be a crappy valve cover, Ill buy a new OWM Cover and develop a CF skin cover for it...

 

I used to do that too until one day I noticed I had a misfire right after new plugs and found the arm touching the element. Now I used a magnet.

 

Since the Vanos cleaning and oil change 2 days ago, I have had the code pop up only once during idle yesterday and not since - but Im sure I will continue to get it here and there. I will be doing another oil change in a week and replace the check valves. It seems that the oil itself and build up was ultimately the issue. Thank you guys for all your help, I would of been chasing my tail for months without it and it is very much appreciated. I ordered a smoke machine to test the valve cover/pcv system and check over the entire engine when it arrives.