I have idled my 2004 taurus and unplugged the IACV and the car still runs. I am assuming this must mean I have a vacuum leak somewhere. I have checked the PVC hose, no cracks, excellent condition. What can I do to find the vacuum leak?
try spraying carb cleaner buy the intake gaskets etc. if the idle slows down to about noraml for a second after spraying a spot you found it. you do not have to use much. that or hissing can be a indicator of a leak.
Try taking a piece of hose, like old garden hose. Hold one end to your ear, take the other end and move it around over the engine listening for a hissing sound. This technique will help you pinpoint a sound over the noise of a running engine.