Loss of power/excessive idle

Hey guys,

I'm new here and I have a 2007 Chevy Aveo5 that's running rough. It just started today. When I bought the car, it had a CEL on which stated an oxygen sensor or cat was bad. I haven't replaced either. Problems I'm having now are rough idle at around 1300 RPM, when I put it in gear there is no power even if I floor it, It tends to pull when in gear with no throttle, the exhaust is significantly louder and resembles a helicopter's sound. I found a vacuum leak, repaired it and it didn't fix the problem. Any help is greatly appreciated.

well your exhaust is loud, no power and a cel pointing to the cat... i would check the cat.

if your not going to do that, mist the wires on the ignition systel and look for a light show, do the spark plugs, and pray the cats hollowed itself out, instead of clogged.