Carb Tuning / Vacuum Problems?

The idle mix screws have been a lot more responsive now that I plugged the exhaust crossover holes in the manifold, and I've been able to get the idle speed lower, so what you're saying makes sense.

I also posted this over in electrical but maybe it's better off here since this is sort of the catchall thread for my issues:

Question time for the coil. I have 2 wires going to the coil, plus a blue/green one that I know is from the tach. One is thicker, black with a brown tracer. The other is thinner, black with a yellow tracer. The way it's been hooked up since I got it is:

Thinner black wire, tach, and condenser to coil +
Thicker black (brown tracer) to coil -

Now the book I have says thin black with yellow tracer to - and brown to +. Has my coil been hooked up backwards since I got the car? If so, how the heck did it run? These wires are definitely from a factory looking harness, they haven't been spliced in anywhere. Colors stay the same through a big 8-pin connector.