wheres the pcv valve?

I have a 97 318ti, and I am trying to put some seafoam in my car for a decarb, but I can't find the PCV valve. You either put the seafoam in the brake line booster or pcv valve, but the car wouldnt keep an idle for more than a few seconds without shutting down (when removing the booster hose), so I need to locate my pcv valve because the brake line booster option did not work. If anyone could help me i'd appreciate it :)

answer is, it does not have a pcv valve in the normal sense. it has a little round vent valve attached directly to the intake, with a hose going to the valve cover on a 4 cylinder engine.