Running rich question ???

Hi, I was wondering if a hollowed cat can make a car run rich ? I ask this because my
donor car ran rich before i took it apart. When i removed the exhaust i noticed
all the ceramic material from the cat. had broken off and got pushed back into the muffler.
I read up on how the CTS sensor is a common failure on these engines and can cause a rich condition,
however I noticed the PO installed a brand new CTS. The car would only run for a while before it stalled and I
would have to wait for it (45 minutes) before it would start. i also found out that by resetting the PCM the car would
start up and run for about 5 minutes then it would do it all over again. Any comments would be greatly appreciated .

no one ?

i wouldnt think the cat being gutted would cause that big of an issue. my guess is the o2 sensors are shot and thats why its running like that, and could be why the cat gutted itself.