Pontiac Grand Am

I own a 2001 pontiac grand am gt. About 6 months ago my car wouldn't start; I had it towed to a shop; they couldnt find anything wrong at that time.A few months later my service engine light came on. I switched to a higher grade of fuel and it went off. However a month later came back on. A second time I couldnt get my car started; it turned out to be the fuel pump and that cost me lots of money to fix. They can't figure out what is causing the service engine soon light to come on. About 2 weeks ago I noticed while driving home my brakes were grabbing and then my abs & trac off light and check vehicle soon light came on. It is a mystery to my mechanic what is causing these problems. Any ideas? I'm worried my car will not only fail inspection but cost me more money; I already doughed out over $700 just for a fuel pump and labor costs. Any help would be appreciated.
May 20, 2006.

What codes are stored in the computer?

If I remember right it's 0422 or something like that; it says catalytic converter is not firing right.

Jul 25, 2006.