Okay, I finally broke down and figured out the problems I've been having with the IAC on my 3.1 refit. I had to replace the nylong pipe that runs from the PCV nipple on the rear of the intake manifold, and used rubber heater hose and a couple of PVC pipe parts to replace it. Now, I can start the engine easier, and the RPM's do drop when the ECM enters closed loop operation, but I have a different problem now. A lot of the time, when I let off of the gas and push in the clutch, the RPM's don't drop, they RISE, sometimes close to 3000 RPM. I have adjusted the TPS to .45 volt (I know the setting is supposed to be .55 VDC, thought this might help, but it doesn't). The only thing I can think of is that I am running an AT ECM instead of one designed for my T-5 car. Is that the difference? I'm with this thing.

 

my brother is having the same issue with his G/Fs pontiac grand am with a 3.1. if he finds out what it is i will post up.

 

Update:
Running 17" Hg vacuum off of the plenum Tee.
10* BTDC stock timing.
Still have a mild sound of a vac leak at acceleration, have yet to find out why.
Air intake tubing does NOT leak, tested when installed.
Unplug one of my spare vac lines (I have the evap can disconnected at the moment due to lack of small dia hose) and the RPM's rise.
Have NOT driven car with EST disconnected, but at standstill with no EST, engine seems better.