Actually, the IAC was the very first thing I replaced. I've had them go bad on many of my cars before with identical symptoms. The problems with the brakes not working/being very hard to use existed before the IAC replacement, and I thought maybe that was due to the engine idling so low, bogging down, even dying, it wasn't getting sufficient vacuum pressure. When the brake problem still existed after I replaced the IAC, and so did the other problems, I was 99% sure it had to be a vacuum leak.
