Difficult Start (Cranks Okay)

Check air induction system for cracks and restriction.
Check engine coolant temperature sensor operation.
Check for cracks and poor connections at throttle body.
Check ignition coils primary connections and wiring harness.
Ensure EGR valve operation is correct.
Ensure wiring harness and connectors are not broken or loose.
Ensure engine has sufficient compression.
Ensure fuel injector operation is correct.
Ensure fuel system pressure and volume are correct.
Ensure fuel system residual pressure is correct.
Ensure ignition and valve timing are correct.
Check ignition coils.
Ensure PCM has correct voltage supply and is properly grounded.
Ensure vacuum hoses are not disconnected or damaged.