I had a similar problem with my 355 SBC in my Abone. I bought the car already completed and didn't have specs on the engine. I replaced all filters, plugs, belts etc. I also replaced the PCV valve. That's when my problems started! Turned out I replaced it with the wrong valve!!! The original didn't have any id numbers on it so I thought if it looked the same.....well I was wrong. I had a friend that suggested the correct PCV valve and haven't had a problem since! Might be worth the try!

Pat