I haven't seen the cruise control on the V'gons, but if it's anything like
the one found on my old Audi, there is a rod going from the throttle to a
vacuum "bell" that has a vacuum line coming out the opposite end from the
rod,.I'd say if the setup is like I just described, there is a leak
somewhere. Either in the vacuum hose or more likely the "bell".

Try not to flame too much if I'm wrong :)

Sean B.
'90 V'gon, "Happy Bus"