I have the same year, car. Drive over a bump or whatever causes the rattle you notice but step on the parking brake a little before you go over it. Rattle gone? Jack it up and get under there and check out the emergency/parking brake cable that connects to a Y-cable split junction where you are talking about. The cables are probably a little loose there. You'll see a nut that tightens and loosens the tension. The connection is trampolining up and down and hitting the frame. Get an extension and wratchet up there and tighten it a bit. Then get in the car and step on and release the parking brake a few times. Go back under and check the tension and adjust if necessary. Mine hasn't come back since! Good luck.