I'm pulling 13-15" of vacuum @ idle of 1000 rpm. I'm letting the car completely warm up right now, to see what it does. I'd like to know if the iac being out of whack could cause my car to be idling high + low vacuum? I know it seems like a vacuum leak, but I've gone over every vacuum connection + manifold gasket, with some starting fluid, and no 'idle up' anywhere...

 

It's been said there have been UFO abductions caused by whacked out IACs.
Yes, if the IAC is off kilter, you can fight a host of problems.

 

What is in the engine for a cam? I know the stock 3.1's idle with high manifold pressure (low vac), at about 58KPa at 800 RPM.

RBob.

 

I'd actually doubt that the low vacuum is CAUSED by the IAC though. Low timing can require the IAC to be more open to maintain idle, which would drop the vacuum. IMO, if air is getting through the throttle at a common point, then (on MPI that is - TBI would have some fuel effects) it doesn't really matter - choked airflow is choked airflow.
A vacuum leak on the other hand can cause low vacuum, due to the fact that it can be focused on a single cylinder cuasing it to misfire, which requires the IAC to sometimes open to get the other cylinders to make more power to make up for the dead hole (a huge vac leak is different of coarse). Any misfire can cause the same thing.
The turbos in the exhaust can also cause lower vacuum, due to the increased backpressure and increased residual exhaust gas in the cylinder - and at idle any amount can show up easily.

 

Ahh... I didn't think of the backpressure from the turbo causing it. I've got a 3.1, with a 204/214 @ .050" cam, .422/.444" lift. It's actually pretty mild, in my opinion... I'm idling with about 13-15" of vacuum.

I can't seem to find a leak, and no leaking under boost, so should I stop worrying about it?