I'm still sorting my surging idle after a 09 manifold swap. If I plug the hole on the upper left in side of the stock throttle body, it idles PERFECT!!!

What does this hole on the upper left inside the tb do? Its not the IACV port on the bottom.

If plugging this hole makes my idle perfect, what is this telling me I need to fix? Surely this hole is here for a reason....

 

I Had That Problem. It Was The Iavc stuck. Took It Off, Carb Cleaner. Good To Go.

 

IACV is on the bottom and uses the bottom hole/rectangle. I've cleaned the heck out of it and it is spotless. It is working fine. I'm talking about the upper left hole inside the TB.

 

Turns out it is part of the idle air circuit. The screw ontop of the TB facing you as you look into the TB adjusts how much air is let past it.

The reason mine was pulling so much air into it was because the lousy P2R thermal gasket in conjunction with their 09 manifold spacer was not sealing on this circuit on the backside of the TB causing yet another vacuum leak.....

I'll add this to my "How to get a P2R adapter to actually work" thread...