Toyota Repair: 2002 Echo with a P0420, muffler shop, lean air

Question
My car is having issues starting. When I start the car the engine catches and then dies. If i start the car and give it gas for about 5 minutes it catches. I took the car to my local dealer and they scanned it and found a host of codes P0171, P0500, P0440, P0441, P0446 as well as the P0420. They explained to me that the issues pertaining to the other codes could be causing the P0420 code (replace the cat) and suggested doing all of the other jobs first. I did all of the suggested work ($600.00) with the hopes that this code would go away. Unfortunately no such luck. To replace the cat I am looking at $900 plus just for parts. My question is would the Cat cause the car to do this and is the price accurate?
Thanx
Rob

Answer
The only code that could affect the cat converter is the po171 which is a lean air/fuel condition, the other codes 440-446 are emission control related but will not affect converter performance, the are fuel evap system leak codes, the 420 is most of the time a catalityc converter malfunction so I'm sure it needs to be replaced, the cat could not have caused the other problems, the lean condition could have caused the cat to fail, I don't think the 500 code is related, I can't look it up right now but I think it's a speed sensor code or an idle control malfunction code. Check with a muffler shop, they can weld in an aftermarket cat for about half that price including parts and labor.