On a car that sat that long and only has had a few miles out on it since, I would want to try a good, hard run using a lower gear range , preferably up hills to create as much of a load as you can..that will clean that cat out.
Then drive a few normal drive cycles to have evertying adapt back to normal..You wiil know if the cat is cleaning b/c you will smell rotten eggs.
A cleaned cat and o2 sensor may just do it....check the air filter while you are at it...
Try it before motgaging the house..