its called moosing...its a noise that comes from the IAC hose. If you do a search for moosing or Throttle Hang fix (TH fix) it will provide you with tons of info. Also in the how-to section there is a how to for the TH fix. That will take care of it. I did it, super easy and it worked (I did it when I had the stock intake) and it took care of it. Now that I have an open end it rears its head every once in a while. I will have to experiment with a different hole size to get rid of it. Somebody else on here decided to just clamp the middle of the IAC hose and that worked as well.
Make sure you reset your computer after doing the fix.
