Chevrolet Repair: raw fuel in exhaust on 2004 Impala from defective coil pack, oxygen sensors, o2 sensors

Question
replaced the catalytic converter and resonator on a 2004 Impala 3.8L. The engine was also missing bad and replaced plugs and wires. Still having problems with extremely rough engine idle so a friend checked it with a diagnostic machine. Found that a bad coil pac was another problem. But through all of these processes and driving for about a week found that now fuel has leaked into the catalytic converter and exhaust. Holding your hand at tail pipe there is no pressure. So now to remove total exhaust system.....can this be cleaned and reinstalled? Any advice? Please help!!

Answer
HI JAMES,I WILL ASSUME THAT THE ENGINE NOW RUNS GOOD..IF NOT THIS NEEDS TO BE ADDRESSED ASAP..
SO LETS SAY NOW THE ENGINE IS RUNNING GOOD,NO SKIPS. THE CONVERTORS CAN NOT BE REMOVED AND CLEANED.I DO NOT KNOW HOW YOU KNOW THAT THERE IS RAW FUEL IN THE EXH ???THIS WILL ALWAYS SMELL LIKE FUEL TO A POINT !!! IF THEY ARE PLUGGED THEY ARE BAD. HOWEVER IF THE EXHAUST SYSTEM IS PARTIALLY PLUGGED THIS CAR SHOULD HAVE LITTLE POWER ON THE OPEN RUN [SLUGGISH]LIKE A PLUGGED FUEL FILTER WOULD DO..TRY TO RAISE THE IDLE ABOUT 1800 RPM AND CK THE EXH PIPE LIKE THIS,I THINK YOU WILL FIND THAT THERE IS PLENTY OF EXH COMING OUT..IF YOU FEEL THE CAR IS SLUGGISH ON THE OPEN ROAD, REMOVE BOTH THE O2 SENSORS BEFORE THE CONVERTORS AND DRIVE IT LIKE THIS JUST FOR A TEST. IF POWER INCREASES THEN THE EXH IS PARTIALLY PLUGGED.IF NO DIFFERENCE THEN THE EXH SYS IS OK.[THIS WILL BE LOUD LIKE THIS DONT PANIC]. HOWEVER LETS SAY YOU GET A CK ENG LIGHT AND THE CODE IS FOR CONVERTOR EFFIENCY FAULT.. SO THIS MEANS THAT THE CONVERTOR WAS DAMAGED WHEN THE ENG WAS MISSING..HOWEVER IF THIS CAT IS NEW OR NEWER I WOULD BE LOOKING INTO THE OXYGEN SENSORS THEY DO NOT LIKE RAW GAS. THIS WILL ALSO CAUSE A RICH CONDITION IF THE O2 SENSORS ARE FAULTY. WHICH IF THEY WERE, THEY WILL POP THE CK ENG LIGHT ON. IF THIS HAPPENS CK THE CODES FIRST BEFORE DOING ANYTHING..LET ME KNOW HOW YOU MAKE OUT AND GOOD LUCK TO YOU,,,TOM..