Mike,
This is an annoying problem to fix. Several things to try:
Take the trim panel(s) off the door(s). Make sure all the linkage and devices are where they belong except for the ones that can't (maybe you can tape them in place). Get a friend to drive down a deserted bumpy road and find just what is really going on. Maybe you can actually touch the rattling parts and hold them to ensure you have the right ones.
Rattling linkage (thin metal rods) can be wrapped in heat shrink. Maybe feed it over the connecting joint areas but don't shrink that area. Other areas can be wrapped with foam or something. Use adhesive and/or Duct Tape to hold it in place. Plastic parts that act like guides that aren't fitting properly or are broken, need to be replaced as do any mechanism that rattles in itself (Latch Mechanism, etc.) Hinges sometimes have plastic sleeves that go over the pins and these fail allowing movement and either the sleeves and/or the pins need to be replaced. If the holes in the hinges have enlarged, replace them if they are attached by bolts. If not, you have to get creative or you are SOL.
If you get it all under control, you can go even further by adding a product called Dynamat Xtreme over the door, under the trim panel. Also you can put some strips on the outer sheet metal of the door or man-made material carpet with spray adhesive like jol50 suggests.
If none of this works, buy a used door from the junk yard or sell it and get another!
Good luck and let us know how you make out!
Regards//Keith
