Spark plugs & problems associated

No, a rattle is most probably a loose exhaust heat shield.

Do you have a CEL for a misfire? If not then indeed I'd secure or tear off loose heat shields before digging deeper. You've got at least a dozen exhaust points that can rattle under there. Bang on them with a rubber hammer to test, and then secure, tear off, or pin with long nails to bind shields away from inner pipes.

If shields are quiet and you have a SHUDDER and stumble upon acceleration look for a spark-damaged white spot on any ignition wire dressed too closely to the intake manifold's metalware. Damp weather will increase chance of incidence. Report further. Ern