Will it consistently start after three or four cranks, or does it sometimes not start at all? If it sometimes won't start at all, suspect the main relay. But if always starts eventually, it could be a bunch of other things as well.

You might have a flaky electrical connection at the starter. Might be an ignition switch getting ready to go. Might even be a fuel pressure regulator losing pressure causing you to have to crank it a few times to build up the fuel pressure. If it ONLY does it when the engine is fully warmed up (but NEVER when it's cold) it could be a coolant temp sensor.

Bottom line... you might have to poke around.