Interior lights flickering and radio shuts off when clutch is fully pressed in along with a very strange noise

So I recently got a 2000 mercury cougar
for an amazing price it's in perfect
condition other than one problem and I can
not for the life of me figure out what it is.
The car idles fine and I can put the clutch
most of the way down, but when I put the
clutch down as far as it can possibly go,
the dash lights start flickering, the radio
shuts off, and I can hear a very loud
pulsing buzzing noise coming from the
engine (or something in that area) I know a
lot of people who are pretty into cars and
know pretty much about them but no one
who I've talked to has ever heard of
anything like this happening or has any
clue what it might be.