My idle is relatively smooth, only a little high when I am warming up (not counting the cold start time).
After some hard driving when the engine warms up it drops way down, and starts bouncing, occasionally stalling or almost stalling. after some normal driving it will get a little better, but still bouncy.

Here's the kicker though, if I turn on the AC, the idle goes back up to normal, and barely moves.

I'm doing a bunch of routine maintance this weekend, and was going to tackle this problem at the same time. Right now I'm going to start by checking out the fast idle, ect, but the AC thing kinda threw me off.

 

When my TII's BAC (bypass air control)valve puked I had the exact opposite happen. It would not open and the idle would bounce, or car would stall, with the accessories and the A/C on.

Logic leads me to think your BAC valve may possibly be stuck open. If you search this forum for "BAC" to find how to test it. If you search the word "Idle", you will find a thousand or so posts to help you!!

Good Luck!
Mike