There is a vacuum port of some kind on the top of the engine toward the
drivers side. Right where the air intake connects to the intake manifold.  

What is it?

The reason I ask is because there is a rubber boot that connects this valve
or whatever to a plastic tube that goes off behind the engine somewhere. This
boot has a big hole in it which I have taped up for now. I need to know what
to call it when I go to get a new one. It's a couple inches long and has a 90
degree bend in it. I never got the shop manual for this beast, there's not
much I am equipped to do on this van. I think I can handle replacing this boot
though...

Thanks for any info.

Tom

p.s. Oddly enough, since I taped this boot up the mysterious coolant loss I
was experiencing seems to have cleared up. Could this be related to that? I
can't imagine how.