I know this is old. But maybe it’ll help someone.
I was having an issue with poor idle(drops to 300-400RPMs) and intermittent multiple random misfire at higher acceleration (flashing check engine light, no codes)

I decided to clean the EGR, replace spark plugs, and replace valve cover gasket(small leak into spark plug well)

While removing the valve cover, there is a hose, which connects to the right back of the valve cover, there was a yellow goop, like water and oil mixed. But nothing ever in the oil changes or coolant.
I cleaned this as well as the channel in the valve cover that leads to the PCV

After doing these things the car runs much better. Not sure which one of these did the trick.
But I am wondering if it was that goop not allowing the crank case to vent properly.

I never followed where that hose goes. But photos online seem to show it leads to the crank case to allow oil vent.
When I have time, I want to remove this hose completely and clean it.