I had a laser with eratic starting - it would crank but not start sometimes, turned out to be the little pickup unit in the distributer it took the place of the old points system and its about the size of a matchbox. I replaced it and all was right in the world again.
Also if yours is Automatic transmission there is a neutral start (saftey) switch on the auto. trans. usualy sits on the gear select shaft going into the trans. It stops engine cranking and starting in any gear, only if park or neutral is selected will it allow a start. It can become lose, out of adjustment or dirty inside or unpluged. Turn your ignition on but don't start engine, then place gear selection in Reverse, then check if your reverse lights have come on at the rear of the vehicle. If not on your neutral start switch is out of adjustment or dirty, or coming unpluged etc. Try wiggling the gear shift selection in the car as you try to start it in park or neutral, if it starts near a drive gear selection this will also indicate a neutral switch is out of adjustment or dirty, or coming unpluged etc. WARNING! Make sure that the vehicle will not start in any position except park or neutral if you make any attemp to adjust the neutral switch. Good luck!
