My 2001 Grand Prix isn't running right

I can get it to turn over when I try to
start it but it won't keep running by
itself. I have to push on the gas pedal
to get it to run. When I let up off the
gas pedal, it just dies. It sounds fine
when I let it run while pushing the
gas, it doesn't sputter or anything
like that. I had the battery charged
but it still won't run right.