V6 - plugs and leads covered in oil

[LB81]

Hi,

I tried a search, without much joy so...

The V6 is running a bit lumpy, so I started to check the condition of the ignition system and every one of the plug bore's are full of oil. Would I be right to assume this is simply a worn / leaking rocker gasket, or something more onerous? Interestingly, both cylinder banks have the same issue, yet a separate gasket each side I would imagine...?

EDIT: I have just managed to snap a plastic breather hose that routes from a joint to a breather hole in the top of bank 1's cover, it was really brittle and have discovered it to be almost completely blocked with crud, as is the hole in the top of the cover... could this cause a pressure build up enough to make the gaskets leak?

Thanks in advance
Rich