kradNZ

That link is dead, found possibly the same article here. https://www.tomorrowstechnician.com/undercover-straight-talk-on-subaru-steering-service/

I think you're right. 155,000 km!

So found root cause of the misfire. I've never seen such bad plugs before. No idea how old they were.

Bonus pic, passenger side, valve cover removed. Pretty tidy in there. Still have old tube seals attached here.

Today I replaced tube seals and valve cover seals as I had a worsening misfire. I found oil in all four sparkplug tubes. This was pretty straightforward job in the end. While doing this I was keeping an eye out for my PCV. I found this red fitting (pic attached), but I'm not sure if this is the PCV or not? I have the service manual but it's really not clear. Anyone know where it is in the basic bp5 sohc 2.0i model. Not sure how to delete spoiler field. This is what I found in the manual. Is this actually where it is?