2004 grand am starting problem?

The car has the auto start feature or whatever it is called that you just hit the key and let it go and it turns over for a certain amount of time till started or if it doesn't start it shuts back off within a time. Every once in awhile when you hit the key it just turns over but wont even try to start, just turns over and over then shuts off. Sometimes it will do it 5 or 6 times without starting then will fire right up and other times it will do it 15 or 25 times or more and then it will just fire up with no inclination of any problems and no engine light or anything. Just changed plugs and wires about 10 thousand miles ago and that didn't seem to help any. Can hear the fuel pump run when it is supposed to, am just wondering if anyone has came across this prob. before. Thank you