Vacuum leak in control pressure regulator?

[Eyvind Spangen]

The control pressure regulator in my car makes a bad hissing noise,
just like a vacuum leak. It has got two ports, one on top connecting
to the intake and one "vent" port on the side. The car seems to behave
normal, but if I remove and plug the vacuum connection, it idles a bit
smoother.

Should I just replace the regulator with a used one? I can't think it
should be like this..

--
E. Spangen
'86 Audi 100 2.2 CS quattro