Saab: HELP! Momentary Electrical Shutdown Stops Engine Dead

It's a '95 900 Turbo Convertible, and I love it even so. Sometimes, when
you put a surge load on the electrical system, as by applying brakes,
pressing the electric window button or hitting the A/C, the system voltage
either drops severely or momentarily cuts out completely -- for a split
second only, but enough to shut the engine down. Confoundingly, the
problem is intermittent. I put a new battery in, and the problem went away,
but returned a month later. It's got a brand new Delco alternator, which
maintains 14 volts with a mild load and drops to about 13.6 with lights and
all accessories running. When I clean every ground and hot connection I can
locate, including the battery terminals, the problem sometimes ceases for
week or so and returns. This, despite the fact that I've run a "sister"
cable from battery ground to the engine, and have cleaned the battery
ground-to-chassis connection more times than I can remember. Is it
possible that there's a faulty circuit board that intermittently goes fritzy
when the voltage drops? Anybody?

"Tom" <com> wrote in message
news:brjqrt$d$btinternet.com... 
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I've just had this exact same problem - the mechanics have diagnosed it as
the electrical half of the ignition switch, which is being replaced right
now. It was nice to be able to point them in the right direction after
reading this. Thanks for your (indirect) help!

absgt
1997 9000 CSE