Clear the codes.
Then what drivability problems are there?
How long does it take for the codes to return?
After awhile you have to start all over again fresh on the problem and not keep getting confused with old history.
Your dealer could have looked at the ox sensor operation to first determine their health after replacing the cats.
If they are functioning then the fault is not with them but the signal getting back to the PCM.
Since there is a single cylinder fault, the problem is right there at that point in either the plug, the cop, the boot, the wireing or an injector OR cylinder health. Is the plug fouling, dry etc?
You are at the typical point of trying to fix with mechanical thinking when some in depth is in order.
Translated, you can't rely on just the codes without getting into the total operation, when parts replacement doesn't do it..