Oil in air filter

[Oreo]

Hi All

My 92 2 litre 102 enigne is being plaqued with oil going into the air filter. The oil is coming from the cam cover and coats the CIS plate. I checked all the hoses, cleaned the little metering hole, cleaned the oil vapor separator in the cam cover (everything was already clean actually). In the end, I put a little foam sponge in the air filter where there's a little box for the blowby. I wonder if there is supposed to be a filter for it in there?

I can't seem to produce any significant blowby when I rev the engine either so I'm stumped. I read the the 102 engine is prone to oil vapor in the filter. Is there a solution to this eg an upgrade oil vapor sperator? higher viscosity (5W-40 now)?

BTW, how does the PCV system with the metering hole work?

Regards
Oreo