[Hedgapple]

I was able to determine source of the vacuum leak by first isolating it to the general area by using a length of plastic tubing as a stethoscope. This is more difficult than you would think. Then to confirm that it was #4 I dripped a small amount of water on the joint between the head and the lower intake manifold. The water plugged the leak and whistle stopped (for about five minutes). After I pulled the injector rail I could see the "missing" section of gasket.
The most difficult part of this repair is the lower bolt for the intake manifold support. I just loosened it enough so the bracket dropped back far enough to pull out the lower intake manifold. Without pulling the radiator I think it would be impossible to start the bolt while lining up the bracket.

Regards!