Ford Repair: 2005 ford escape, fuel mileage, auto zone

Question
My daughters engine light came on few months back and said emmissions system check (didnt tell me) she took it to midas they reset it and told her if it didnt come on again it wasnt nothing to worry about. Well it just did it again and i took it to auto zone and the code was p0430. Went back to midas and they said it was the catallac converter and would cost $1000 to fix it. i was also told buy another person it could be the 02 sensor. she has been complaining that the car is eating up gas quick and it also feels like the car is vibrating when stopped at a light and soons you go it stops. So I was wondering if it really could be the catalac converter. She has to go back to school tuesday in maryland so i feel rushed to take it to midas but am a little weiry. Big difference in price between that and an 02 sensor. thanks for any advice marsha

Answer
Unfortunatley, this code comes on for one reason and one reason only. there is no diagnosis. it will need a new converter. as far as the fuel mileage, it could affect it, when the converters burn out- there is a lack of back pressure from the exhaust to the engine. and the computer can't compensate