corolla crank issue

I changed the starter, after one day, I go to school, and I leave the car under the sun for 6 hours, and I start the car, the car crank longer than usual before it starts. It sometimes do that in the morning, too.
I changed the temperature sensor 4 months ago, spark plugs and wires are new, and I changed the fuel tank before I changed the starter.
Why the car crank longer than usual?