Well, I think some of the more senior guys should pipe in on this one.
But if your cat keeps getting clogged, its due to the misfire you're getting from the engine non? Lack of spark and build up of fuel + late spark creates that overly rich mixture that will eventually clog up your cat with hydrocarbons....Now, are your o2 sensors all good? It would be a good place to look as well. If they're faulty it would create misfiring of a perfectly good cylinder and down the line clogging your cat.
Which codes is it tripping? Can you tell which bank is misfiring? Try swapping around the plugs. If the new code changes bank, it can be the plug. If it stays, it can be a number of things including the coil/boot(arcing) and creating that code.
That oil thing is a big issue. Be very careful of your oil consumption because those 2.3's will burn and cause oil starvation; even if it shows you have a full engine, itll still be 1-2qts low or worse. Read the history on those motors, they can be very dodgy and its not out of the ordinary to have a blown motor at 132k.....The car I purchased has 95k and the jack*** spun a rod because he never properly checked the oil.....I'm not sure if there are many oil stabilizers that will slow down the burning, and if a difference with swapping out to synthetic might help....That would be a better question for a more senior mech.
Not to make you paranoid. Just be careful. Hope this helps a bit. Let me know if you make any headway