Chrysler used little green felt / velvet pads on all of the trim mounting tabs to keep them from rattling, and I thought to myself "Why can't I do that?"
The bodies of our relatively low cost cars flex and twist over time. Things will never fit as tight as the factory once a few miles have been put under it. You can use a ton of dyna-mat and that will pretty much help but it will take some work to quiet her down. I groan and moan in my old age so I have no problems with "Wildfire" creaking and rattling after all these years.