Why won't my car start?

My 06 Grand Prix will crank but won't start. When I spray starting fluid in the throttle body the car sounds like it's about to start and it will do this for about 9 seconds but then it gives up and keeps cranking. It only does this while I press the gas pedal down repeatedly otherwise it will just crank.... show more My 06 Grand Prix will crank but won't start. When I spray starting fluid in the throttle body the car sounds like it's about to start and it will do this for about 9 seconds but then it gives up and keeps cranking. It only does this while I press the gas pedal down repeatedly otherwise it will just crank. Smoke starts coming out of the exhaust and from the engine while I'm cranking the car. The engine is a 3.8 series 3. The spark plugs and the fuel pump are new. Is the starter a possible cause or is it the fuel injectors that are my problem?
Update: I have replaced the starter and the car cranks normally. Is the problem the fuel injectors, the ignition coils, or the crankshaft position sensor?
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