The hose you are referring to is the blowby gas/engine breather hose that runs from the passenger side intake manifold to the throttle body and has nothing to do with the PCV system. - Peter
Actually, it's an integral component of the PCV system. People have played w/ this one for years. Blowby introduced into the intake vs. unmetered air and invalid MAP readings.
Keep all vacuum fittings intact and/or upgraded. This includes the entire PCV circuit (both driver's and passenger side).
What DOES reduce passenger side PCV circuit oil/blowby is a chambered design breather which prevents oil from readily being introduced to the intake manifold and this:
GM part# 12572717
What the pic doesn't show is the "fixed orifice" design of this valve. Been using it recently, and it does just what it's supposed to do.