Besides what
@strutaeng noted, I'll add a couple of things.
Next time it won't start, hold the accelerator pedal to the floor to use clear flood mode. Crank it with the pedal on the floor and, if it starts, you likely have a leaky fuel injector or an evap purge valve that's not closing. That would mean that fuel or fuel vapor is getting into the cylinders or intake, which shouldn't happen with the ignition off.
When it won't start, does the tach move while you're cranking it? On a cold start watch the tach while you crank it to see how it acts; then you'll know how it SHOULD act when you're having trouble.
Lastly, it wouldn't hurt to have a Crankshaft Variation Relearn procedure done with a capable scanner, just to rule that out.