Codes p1083 and p1084

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Check engine light came on. Ran the scanner and got the codes p1083 and p1084. Engine idles rough, hesitates slightly. Temp on catalytic converter read hotter in front than in back. Had spark plugs and wires replaced, fuel filter replaced, O2 sensor replaced by Catalytic Converter. My mechanic said to try fuel injector cleaner to see if it clears up the rough idle. I do know there is a crack in my muffler, but would that cause the rough idle and engine light to come on?