Originally Posted by upallnight

Great mechanics since they couldn't figure out that the cats were breaking up and clogging the exhaust. Their reply that it was "PROBABLY THE PROBLEM" does not leave me with a warm and fuzzy feeling inside. But hey that just me.

The cats were the problem because something made the cats the problem. Mixture is controlled by O2 sensors and if you have a bad O2 sensor eventually the mixture will also destroy your new cats.

If you read the postings by MrProject he noted that he didn't want to drive the car and risk destroying the new cats until he was sure his problem was solved.

If you don't fix the problem now, you will be posting later why your new cats are clogged again.