1997 Pontiac Grand Am Car doesn't start up right away

Engine Performance problem
1997 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic

Ok here is the deal. 2 years ago, car was misfiring on 2 cylinders and was repaired by a local shop. Last year, had fuel problems. Local shop replaced fuel pump, fuel rail, injectors, fuel filter, and I also had them do a full tune-up on the car. 3 days ago. My dad took the car to the local store and couldn't get the car to start. When I got to the store, I was able to get the car started and followed him home. Now, I have gone out and played with the car a little bit. When you strike the key, the car will crank but will not start. If you sit there for 30 seconds to 1 minute and try again the car 85% of the time will start. Every now and then it'll take a few tries. What could the problem be? When you strike the key you can hear the fuel pump whirring, so I don't believe that is the issue, especially with it being so new. Could it be a sensor (O2, EGR, etc.)?