Car was running fine, then went to go somewhere and it fired up and as i drove out of the driveway it choked out and stalled. Had it towed to a shop and they said it was a fuel pump...They only replaced that and called and said my car was done..paid 650.00. When i picked it up it barely started,ran really rough and had alot of white smoke coming out tail pipe. I got it home and it hasnt started since. Turns over, but will not start. It has popped a few times. The shop told me I needed spark plugs because they were fouled from bad gas so i replaced those and they said my catalytic converter was plugged like a potato was stuck in it and that is why its not starting. They said if i replace the cat it will start. Is that true? Can a plugged cat make a car not start? I have checked relays,ignition modules, coil pack etc. Also for about a year i had a code come on saying egr valve. What could be causing it not to start?