Difficult To Start

Check for contaminated fuel.
Check fuel pressure.
Check for faulty Throttle Position Sensor (TPS).
Check for faulty coolant temperature sensor.
Check for loss of crank signal to ECM.
Check EGR system.
Check fuel pump relay and circuit.
Check for faulty in-tank fuel pump check valve.
Check ignition system.
Check for faulty IAC operation (if equipped).
Check for incorrect EEPROM application (Impulse and Stylus).
Check for faulty main (or ECM) relay.