My 2004 Dodge Ram 4.7L Quad Cab 4x4 has started to overrev periodically when I accelerate and I am getting some metal clanging on the exhaust somewhere. I have a magnaflow exhaust I installed about 2 years ago. I was thinking catalytic converter but wanted an opinion. No error codes yet. And should I replace both of the converters or just one if I can diagnose which one.