when the car is idling in gear or in park, it has a noticeable rattle from under the hood. when i give it a little gas, and i mean a little, it goes away completely. it isnt a rythmyed rattle, it just flat out rattles like tin kinda only a little deeper sound, and its not the cat heat shield. what else could it be?

 

it could be the exhaust manifold heat shield.

 

what are those attached to? are they on the manifolds or something else?