Have you located the specific site of the rattle? Engine off - tap lightly with one hand and use the other to figure out where it is rattling, ultimatly a little upward pressure/bending took out most of mine. More rattle came from where the 36" heat tube that goes to the air box fit into the shield than anywhere else. If the tube is old the ends could be frayed. Duct tape is a quick fix but won't withstand the heat for long. My tube also rattled where it made the first bend by the radiator under the hose. There should be a metal clamp attached to the frame of the car and that is a source of rattle for the tube. I put a 6-8" length of small dia. vacuum hose over an approx 12" nylon zipper clamp [sorry, proper name block] and cinched it down snug but not ultra tight. Vacuum hose goes under the tube and clamp goes around lower radiator hose and over metal tranny cooler line. Took out 98% of rattle in my 88 245 engine compartment.