When I accelerate hard, I hear what sounds like sand shaking around in a tin can coming from the engine bay. I don't always hear it when I rev the engine, so I'm not sure what's causing it. Anyone have any ideas?

I have an 06 with ~80k miles.

 

Fergy, pop your intake/filter cover: if there are leaves and junk trapped in the box there, they'll whip around like in a tornado when you're at WOT.

 

Thanks! I'll try taking it off tonight.

 

Possibly a loose heat shield? I believe there was a TSB or Service Bulletin for that.

With WOT, a motor mount could also be compromised. Also consider a vacuum or exhaust leak.

Start with the simple suspects and work your way down the list.