1991 Chevy Camaro Why does my car make a rattling noise whe

Hey guys I have a 1992 chevy camaro v8 automatic. Well my question was how come when I accelerate or press on my gas to go faster I hear some rattling noise sort of like a snake but a heavier pitch and it only happens when I try going faster. When I put my foot on that peddle and accelerating at a faster speed it makes some wierd noise like if somethings loose. Also the other day I was going up hill and I was in over drive, ok and my car was going really really slow with that noise I heared that noise alot when I went up hill, and my car was slow I couldnt go any faster my RPM was toooo high. Do you guys think its my transmission or catylic converter or EGR valve or DISTRIBUTER OR fuel Filter.I need to know please cause I dont trust these mechanics these days