The​​ burb is making a rattling sound. I've made a video of it to show that sound and when it's happening which seems to be when the RPM drops to idle or just below idle. It's a metal sort of sort which goes away even if I hit the gas a little bit. Leads me to believe it has something to do with either the pulley system or something is just loose like a skid plate or something. It's coming from the passenger side cabin and engine bay when I open the hood.

 

Is that correct ~500 RPM? I think it should be a bit more...
Using steering wheel also results in decreasing RPM.
~13 y.o. is enough to create "rattling sound" depending od RPM

 

I had a broken weld on my engine oil dipstick neck that caused a similar rattle. A bead of JB Weld fixed it.