Momentary power loss

[tblank@teleport.com (Ted Blank / Webworks)]

I just got my 875KCSTQ back from the shop.  They replaced the exhaust
manifold, power steering pump, and fuse box. (big $$$).  During the test
drive we encountered something new that has them stumped.

When accelerating, the engine will totally shut down for just a second at
about 3500-4000 rpm. It kicks right back in and is smooth as the revs keep
climbing.

It seems electrical rather than mechanical or fuel related.  Current suspect
is the vacumn selenoid associated with the turbo (please excuse my lack of
specificity, I'm pretty new at this)

Your thoughts, ideas, and suggestions are eagerly anticipated.

Thanks in advance
Ted Blank