i was driving home from work tonight in my 92 eg with a b16a and was listening to the exhaust and it sounded like i had a leak, and it got a little louder as i went and then i lost power and it was running really rough, i babied it home and jacked it up and at the rear of the cat it just rusted apart from the exhaust, i only have one o2 sensor before the cat, and i'm confused on how this effects the power and how the car runs if its just exhaust and theres no o2 sensor after the break. any ideas? i'm not too new at the car scene but ive never had an exhaust just snap like that and then the car lose power. thanks for any help

 

Is the remnant cat possibly clogged and restricting exhaust flow? Remove it to see whether the engine runs better.