I have a 2004 Mitsubishi Endeavor when Driving I here this rattle noise....Anyone else have this problem ? Or no what it might be ?

I had to remove the heat sheild from the catalytic converter and put a clamp on the heat shields on the engine manifold. They had rotted away but were still rattling away. Very noisy at certain rpms. I have other problems but by the sounds of yours, it's probably a heat shield rattling.