I've installed cruise control from an old Audi in my '84 Westie and
for the most part it works reasonably well. However, I believe
because of the length of vacuum tubing from front to back of van the
response time between setting & engine reaction is anywhere from
seven to ten mph and sometimes it goes over the set speed
by about five mph before settling back to the set speed. Does anyone
know of a way to make this better?  I also have a Volvo 740 into
which I put the same kind of cruise control from an Audi and it
always stays right on the set speed without varying.