Hard Start/Will Not Start

Check battery and starter.
Check fuel pressure.
Check fuel pump circuit.
Check fuel pressure regulator.
Check fuel injector circuit.
Check fuel evaporative emission circuit.
Check Idle Air Control (IAC) Valve.
Check ignition timing and ignition circuit.
Check timing belt (if equipped).
Check Exhaust Gas Recirculation (EGR) valve.
Check Positive Crankcase Ventilation (PCV) system.
Check Camshaft Position (CMP) sensor circuit.
Check Crankshaft Position (CKP) sensor.
Check Mass Airflow (MAF) sensor circuit.
Check Engine Coolant Temperature (ECT) sensor circuit.
Check main power supply and ground circuits.