Following-up on suggestion that I had a vacuum leak, I found several
suspect pieces of tubing and connectors.  My engine has combination of
rubber/cloth vacuum tubing and hard plastic vacuum tubing.  Can I go
with the rubber/cloth vacuum tubing -- looks like 3 mm ID.

Another suspect point was a fitting that connect a small diameter hard
plastic tube with the tube coming from the axillary air regulator and
the outlet end of the connector goes to the intake manifold.  Where can
I get the connector?  I had dummied up a connector many years ago and I
think it has sprung a leak

Engine in 1.9L in 1984 Vanagon

Thank you,

John