Sounds like a vacuum leak somewhere. I know you said you checked everything, but I'd double check again one more time just to make sure all the clamps are on and where they're supposed to be. Also check the lines that weren't included in the install, but might have gotten bumped loose from the installation, as complicated as you make it sound, something might have been nudged loose just from fighting the intake. But that is not normal. However when revving, it sounds good.
