OTHER than a vacuum leak what else could I be looking for? Anything else?

S5 na motor
Stock other than a cone air filter and bigger exhaust

 

bac issues maybe? i know when mine was bad i had a bouncy idle, but once there was enough electrical load on the alt the idle would smooth out. granted this was on an s4

 

So I did some poking around.
I found an old thread on the forums and Hailers(I believe) had a quick check for the bac.
1) Warm the motor up.
2) Shut the motor off.
3) Unbolt the BAC leaving the wires connected and turn the key on.
I did this and it buzzes very lightly. So, it's not the ecu.

I currently don't have a meter to check if the duty cycle is going up and/or down.
I can easily move it back and forth with my finger so I don't think it's stuck.

Put everything back together. Started the car. Same symptoms.

I pulled off the little tube that feeds the bac from the intake duct. Stuck my finger over the duct side to keep the car running and everything SMOOTHED OUT. Rev'd the motor and it settled back down a little below normal(500-600 rpm), but steady. Note the BAC is still connected electrically and the air inlet is NOT going through the AFM.

So, what does that say? A controlled vacuum leak "fixes" my idle problems?

If I had a vacuum leak like I originally thought shouldn't this make it worse?

 

Only happens when the car is up to temperature.