well, i changed out my egr, adjusted the ignition timing, and new spark plugs, and dribbled small amouts of water into the carb to get rid of some of the carbon ( read about that from some machanic dude ) the rattle is gone and most of the power is back. so you can try some of those ideas. im also thinking about doing the seafoam so ill let you know what happens with that.
right now i am in the process of changing out the head gaskets since 1 or both are blown.
i'll keep you updated if i find any other things that could be the problem and help out.