Pontiac Repair: misfire with load 3800 supercharged Ser I, vacuum leak, bypass valve

Question
Hi Todd...
My sprchrged 3800 starts and revs fine but misfires on 2 or 3 cyls when it is put in gear and is accelerated.  I think I might hear a vacuum leak somewhere.  Does that make sense?  I was reading about the bypass valve and the vacuum tree on the Eaton S but haven't gotten any good ideas.  Can I rule out a manifold leak/crack?

Thanks!

   Emil - Chicago

Answer
Hi Emil:

Yes a vacuum leak would be a logical guess those 2 cylinder do not share anything like a coil so I would look at possably a vacuum leak or maybe even a bad set of plug wires or cracked park plugs. If you looking for a vacuum leak spray some car cleaner around the intake manifold and see if the engine rpm's change while the car is hot and at an idle. If so you found the problem. The gasket betaween the manifold and the super charger on the older ones would go bad usually tight under the nose of the super charger at the front of the engine.