Cranks Normally But Difficult To Start

Check for strong spark.
Check Engine Control Module (ECM) ground and power circuits.
Check intake manifold vacuum. Vacuum should be more than 18.9 in. Hg (1.8L), or 17.7 in. Hg (2.0L), at idle.
Check air filter element.
Check if engine starts with throttle 1/4 open. If engine starts, check for carbon deposit on throttle valve.
Check that engine starts while fuel pump is running.
Check fuel pressure while engine is idling.
Check for fuel injector operation while cranking engine.
Check fuel system holding pressure.
Check terminal voltages of Mass Airflow (MAF) sensor, Throttle Position (TP) sensor, ignition coils and Engine Coolant Temperature (ECT) sensor at Engine Control Module (ECM).
Check for contaminated MAF sensor element.
Check spark plug condition.
Check Idle Air Control (IAC) valve.
Check if engine starts with ECT disconnected.