ill toss out what i can. congrats on the new ride.
some aftermarket IAC's mount upside down. is that what you are referring to?
do original TB's have holes? mine dont. some guys do it to help the IAC, but i thought it swas done by individuals on oem parts.
a stockish healthy motor should have 15-20" of vac at idle. it still sounds like you have a leak (hanging idle till you stab it).
my two cents. good luck.