Thank you to everyone who originally responded to this post. My friend
finally got a chance to work on his bus and here is what he had to say:

*Sorry it took so long to get back to you.  I found a leak in the intake
manifold.  The coolant line that crosses over the engine had a stud that
used to be attached to the intake, but had broken free of it, leaving a hole
in the intake.  I put form a gasket on a bolt, screwed it into the hole, and
like magic the engine idles properly again.

Thanks for the info.
*
So thank you all again - problem solved.

--
Thanks,

Jeff
'85 GL (Gertie)
'90 Carat (Grover - the noble parts donor)
'86 (We call this one Scrap)
'78 Bus (Melissa) Patty's Bus