this sounds like the vacuum hose that runs back to the cam cover and is attached to the cover with a PCV ( pressure control valve) the valve is there to only allow gas out of the engine and not back in and over time the valve can stick open or otherwise fail or the hose may have sprung a leak - this would explain the oil leak and the erratic idle as air is pulled into the engine that hasn't been metered by the MAF sensor
The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements
part 32a looks like the high load breather valve so yes it could the issue
and part 35 looks like the PCV part to me as it should connect to the cam cover
and the cam adjustment is referring to the VVT ( variable valve timing) function
as the cam pulley will move around to boost power and improve drivabilty
this is controlled by the cam position sensor on the cam cover
but could also be a faulty conrol solenoid or a faulty pulley
if you can tell me the exact code I'll try to help further
OK I'd try the vacuum leak test I mentioned earlier
if you remove the oil filler cap with the engine running and the idle speed increase then this is another sign that the breather system is open to the intake and give some direction
regarding the 17927 code this is often an electrical issue and I'd say to 1st clean the connections to the cam position sensor and the VVT actuation solenoid