A have a 2000 chevy 2500 with a 7.4 motor , starts fine in the mornings . After it has warmed up , the motor has to spin over about 15 times before it will start. No check engine light , 60 psi on fuel pressure , new tune up , new fuel pressure regulator.new coolant temp sender

My first thought was the Engine Coolant Temperature (ECT) Sensor. My second thought was that the wrong spark plugs were installed; i.e. not the exact ACDelco plugs that came in the vehicle.