I just got new Toyota struts and Toyota shocks and 2 sway bar links and Toyota wires (mine were from 1998) and Denso plugs and a new valve cover and a new Toyota AC pulley and belt. I heart this rattle on the way home and thought the strut wasn't tight. It was just this "vapor canister purge valve" bouncing on the inside fender well.
This thing runs and rides almost like a new one...
As an aside, I filled it up today and drove about 60 more miles and when I got home I smelled gas and hear noises from my gas cap. I released the cap and screwed it back on and the noises went away. Any possible connection the the broke valve?
It pulls a vacuum in your gas tank to keep vapors from escaping. If there is a split, it can pull unfiltered air into your engine through the intake manifold.