Riddle me this Batman

[XfireZ51]

Got the motor put together and am battling what appears to be a vacuum leak. I first addressed what appeared to be an issue with a sticking throttle. Took primary throttle apart and cleaned off shaft of any "paint" and re-installed throttle blade. Took car out for drive and it actually didn't behave badly but idle speed was a bit high. However the "cruise control" sticking throttle seemed to be fixed. However, I still have what feels like a vacuum leak. Pulled the PCV and the 2 side ports of the plenum. In each case, idle would INCREASE when I exposed them to atmosphere.
My concern is a leak at the throttle body somewhere. It tends to raise idle from 825 commanded to a 975-1000 actual.
Here's what is interesting. when I first start the motor it will "flare" to 1500-1700rpm then idle will drop to 1000 w coolant temps at 50C.
As coolant temp increase I can see the IAC counts drop and so does the idle rpm. OK, so now the motor is idling at about 850 or so with IAC counts of ~ 10. GREAT except then I blip the throttle. IaC counts drop to 0 and now idle has a bit if a surge at about 900-1000. Otherwise the car drives well with no surging at PT cruise. So why does blipping the throttle
upset the apple cart?? Any suggestions before I pull the plenum are appreciated.