Paul,

If you're talking about the cylinder just behind the wall that has the
pink and the white vacuum lines running back into the engine compartment
(which sounds to me you are), the pink one going towards the throttle
will result in severe power loss if disconnected.  Been there, done
that, and not on purpose!  It's not enough of a vacuum leak to kill the
engine, it may only have effect when the throttle is engaged.  I can't
quite remember since it was last summer that I had vacuum problems. But
I seem to recall that it idled okay, but it had no-go syndrome.  I'm not
sure where the white line goes or what it does.

Mine came off because the rubber vacuum piece that connects the pink
plastic line to the throttle was worn and had stretched.  Dealer told me
that the lines themselves virtually never need to be replaced, only the
little connection pieces which are very very cheap (i.e. if you only
need one or two--free; enough to do the whole van 3 or 4 times, $2).

Tonya
87 Vanagon GL Wolfs
74 S. Beetle