Another noise maker is the timing belt can rub and it is a repeating sound that can go away momentarily. The other is the cam tensioner. The belt makes a dull roar sound and are mostly present at the beginning and end of giving it more throttle...when they go from slack to tension and back again. But you likely changed that belt @ 80k miles. A good sound clip vid would be a bonus. Have you gone through and inspected all of your connections from the air filter to the throttle body?
