I replaced my intake manifold and now I have a problem, a large vacuum leak. Even with the throttle body completed blocked off, the car idles at a 700ish rpm. Though it's hard to hear it clearly over the sound of the engine, I can hear the hissing of air being sucked in from where it shouldn't be. My instinct is to spray liquid around the manifold/plenum area and watch it be drawn in. I sprayed methanol, but I don't see or hear it being sucked in. It must be a giant leak to still be idling at 700RPM with the throttle body completely blocked.
What are common places of leakage for the intake manifold assembly? What other techniques might I try to pinpoint this leak?