I have a Grand National that's pulling 16-17 inches of vacuum at idle. The car doesn't want to run under 900 rpms for idle. The car is modified with 120 pound injectors, bigger fuel system, 62-62 turbo, Precision dog house and Accufab throttle body. I have the ECUGN and I have it tuned pretty good. It's running on flex fuel that has about a 80% alcohol content. I have the stock cam with upgraded valve springs and I replaced the stock cam gear set to a heavy duty set. Air to fuel is nice and clean at idle and I have adjusted the timing a bit and it doesn't seem to matter. It idles fine at 940 RPM's but I can't really get it to want to idle under that. Can anyone tell me what they seeing for idle RPM's and how much vacuum? I suspect I have a vacuum leak or two I definitely don't have a boost leak as I am seeing 28 pounds of boost without adjusting the HD actuator too far and it runs really strong under WOT. I was going to go ahead and replace the vacuum block and eliminate the EGR and hoses but before I did that I wanted to see what ever one else is seeing. And the last question is in regards to the IAC motor and where it's set, is there a specific way to set it? Do you set it for a certain voltage with a meter?