Code 420 and gas smelll

Hi,

Can someone please help… I own a 99 Pontiac Sunfire 2.2 about 100k miles and it has been giving me some problems. The engine light came on and I pulled the codes and at first it told me that one of the o2 sensors was bad, and that the TPS was bad. I changed the first o2 sensor and the TPS but the engine light still kept coming on. I talked to different people and they all kept telling me that I needed to change both o2 sensors because if I just change one, they will not be able to communicate as well… I decided to go ahead and change both of them and then the light went off for about 80-100 miles and then it came back on. I pulled the code again thinking it was going to be the o2 sensors again, but this time it gave me code 420 (indicates bank one catalyst system efficiency is minimum requirement)… I have been reading on the net and I have read that the catalyst might not be the problem. I did a tune up hoping that my car could just be misfiring, but the light continues to be on. I have also noticed a strong smell of gas when I start the car or when I stop at a red light. Also, when I take off from a dead stop, the car hesitates but then kicks in and runs normal again. This happens after I have ran the car for a while. I noticed that it hesitates to run and jurks a little after I get off the freeway and run it on regular streets. I was wondering if these problems could be part of the code420 problem. Please help with any suggestions to what I should do next or with any comments… anything will help. Thank you.

Dallas5 try reading this article.

http://www.troublecodes.net/articles/catfailure/

Hey, so what might be happening is your car is running to rich. Like too much gas to air and the excess is not being burnt and running out your exhaust and your catalitic converter is not able to clean all the gas that is coming through.
I have the same trouble code but it is because I took out my catalitic converter..
hope you can figure it out