If the can (hence the line) is clogged it will definitely increase crankcase pressure, as it is a closed system and the pressure has nowhere to go except eventually out the seals. The intake side doesn't matter on a N/A if its sealed or not, its actually better if it is sealed like old style engines that also vented crankcase pressure directly to atmosphere. The intake side on N/A is always a vacuum when running. Actually considering a new can with a vent to atmosphere to avoid this situation. Fundamentally I had the same situation as a stuck closed PCV valve. Its not good, hence the idle issues.