Be sure the PCV vacuum source is BELOW the throttle plates. Be sure also that the opposite side valve cover is vented (also with a baffle) to the atmosphere somehow(usually to the air cleaner housing) The PCV requires the vent to function correctly. Third possibility, excessive blow-by past the piston rings could be the cause, and if excessive blow by is the cause, you may not be able to prevent this by "normal" means. With you already mentioning that the baffle is in place on the PCV side, these three things are the only likely possibilities.
Sometimes, on vehicles that are RACE ONLY, you do not get enough vacuum at full throttle to keep the blow-by down...That is a different story. They have methods on those machines too but I assume we are talking "street Machine" without a turbo or supercharger here.
Richard (Self-Employed, full time professional mechanic.)