Sputtering at Startup

When I start my car it dies. I start it again and it sputters. Finally I get to rev it and it comes alive. I just changed the crank shaft sensor. With gas prices I have also left it at E for a while. Could this be the fuel pump. Does it intermitately do this when it is dying. It sputters even with more than a 1/4 of fuel. Or is this the IAC. Oh and I got a check engine light. Does autozone check codes for free. Because pep boys charged me 20 bucks. I though it was a rip of.

Thanks

Going to autozone then. I'm a college students so I'm really on a tight budget for a 30 dollar charge just to tell me what a code means.