runnin rich problems

well lately my cat plugged up....then a big chunk of cat came out(about the size of my knuckle)...and now my truck is runnin rich with a low lopey idle....what did i mess up?

you didn't say the year and engine size but if it's equipped with a EGR valve then check the back pressure hose and transdeucer at the valve to see if it's burned this happens when there is too much back pressure in the exhaust and also assuming it's fuel injected disconnect the pcm for about 10-15 minutes to reset the adaptive memory

its a 97 with a 318.....i disconected the o2 sensors and the prob has temporaraly cleared up

again disconect the 3 connectors on the pcm make sure the key is off when doing this and wait about 10-15 minutes to reset adaptive memories and reconnect o2 sensor you still may have a faulty o2 sensor but this should be done first because when the cat pluggs up it senses the fuel rich the adaptive cells try to remove fuel then when exhaust flows again pcm tries to compensate and adds too much fuel as it may not be able to meet the threshold to update the adaptive fuel cells