Rooster, It may be a long shot....... Is there a chance that one of the intercooler boots is leaking or loose. Your sound description is alot like CowboyBobs problem a few months ago. He had a boot to come off. Anyhow GOOD LUCK!!!!

 

There wasn't any loss in power though, I'll check them though because I did have a few of them loose.

 

So about them boots, would they be temp related? The colder the ambient temperature is the lower the boost pressure the truck will start to make a noise.

I double checked the valve lash, checked to make sure all the intercooler boots were tight, I didn't see any cracks in any of them, but I guess I could do the red green fix and wrap them in duct tape

 

Just have some one rev the engine and feel for air leaks.