Welcome to the world of FORD!!!! your going to be chasing rattles for as long as you own your system. as soon as you fix one, another will begin. The only way you are truely going to fix it is with expanding foam.
2000 SVT #1633/2150 many mods, many more to come http://www2.gvsu.edu/~hafnerb/11h/car.jpg "If it doesn't fit, force it, if it breaks, it wasn't meant to fit in the first place."