I have searched both under the hood and here... no answers yet.

2001 6.8, California model. I have what sounds like a significant vacuum leak. I have felt all around by the Throttle body and ICV and cannot feel, see or find anything cracked or loose. I also sprayed a bunch of carb cleaner everywhere I suspected and cannot find it. It there a pronounced vacuum sound naturally?

I did check all the elbows I can find with no cracks and the PCV while loose in the grommet and barely sucking vacuum, messing with it does not appear to change the noise.

 

If you have the water heated PCV valve make sure the water loop is installed correctly so that the PCV valve can seat all the way in the crankcase.