[me and my metro]

I understand your question better now.
Pcv systems under ideal conditions pull a slight vacuum on the crankcase. This is for many reasons, one is contain oil vapor emissions. Another and equally important is to remove moisture that can accumulate from normal combustion. Engines that do not vent properly crud up and sludge just ask Chrysler with their 3.5 v6. The solution was to increase pcv flow rates and the engines seem to be better now.
At full throttle or under boost conditions the engine has no vacuum. The engine also has high blowby rates during these conditions. This is when airflow reverses in the hoses in question. If your engine is in poor shape oil vapor or oil blows into the intake and the engine “oil farts”.
The newest cars include all airfow in the mass air calculations for fuel pulse width. Idle quality will change if you open the oil fill cap or just pull out the dipstick. Ford ecoboost vehicles can set a crankcase vent code if the o-ring seal on the dip stick is bad.

For your older Sube you can install small filters on each valve cover and eliminate all the other tubing. Leave the pcv where it is, it pulls off the center of the case.