Positive Crankcase Ventilation. Sounds sort of fancy. What it means is the house connecting the valve cover to the throttle body input was all messed up. The previous owner tried wrapping tape around the end and using a hose clamp. This particular does not use a clamp.

I went to the lowball Chevrolet dealership and picked the correct replacement part.

The split at the end of the hose definitely did not create a tight seal.