Hey, just wanted to post to help someone else at some point. Car was throwing codes for random misfires and cylinder 3 and 4. Once in a while I got a lean at idle and a code for low boost. I'm glad it happened because it made me do a lot of research to learn this engine a lot more. I put in plugs and coil packs a couple months ago, I checked the diverter valve and still issues. Finally I started looking into the PCV valve. I had vacuum at idle in my crank case. You can tell by taking the oil cap off and feeling the suction. Normally at idle you should feel some air putting out not sucking in. The valve was so useless that the intake manifold vacuum was now in the crank. This led to lean at idle issues (sucking in more air then the ecu knew about). It led to boost leaks. As the manifold pressurized with boost it was able to leak into the crank and possibly escape through the rear breathing tube check valve. Most importantly it caused misfires from wrong air fuel mixtures. Hope this helps someone. Replace that PCV with something like BSH PCV Revamp. Though guys are saying catch cans will not save our intake valves from caking up it will slow that oil from going back into the intake tract. That makes your intercooler less efficient and the heat caused by oil vapors returning to solids can lead to combustion issues. I plan to install a catch can after I seen how much oil in this design feeds into the intake preturbo.