Knocking sound coming from intake manifold

[lowhoe]

I have a knocking sound that seems to be coming from my intake manifold does anyone have a clue on what it can be. I have a 04 5.3

 

[dropmech]

Valve train? Piston slap? Does it Happen when the engine is cold or hot or both? Does the sound accelerate along with the engine?

 

[lowhoe]

seems like only when hot and no it doesnt accelerate with engine