I recently had a similar problem on my SEL, also in the left front. Turned out it was the grommet between the airbox and the hose leading from it. It'd make a clunky noise if I stopped quick, went over a curb or sewer cover. I put some silicon goop around it and its resolved.
Might want to check that.
Sent from my HTC-Z710a using FF Mobile
Last edited by Burns098356GX; 02-27-2013 at 10:00 AM.