very hard to start when cold

Mitsibushi 1.5 ECI 5 speed. is very hard to start when the engine is cold, but start very well after  30 seconds runnign or when is hot. I'm changed the Mas Air Flow, Coolant Sensor, O2 Sensor, Spark plug and wires, rotor and distributor.When my car start, my check engine come on after 30 seconds, i'm checking the data and all problems is repared. I'm retesting the data for error code and the computer look nothing codes. my idea is possible the TDC or ECU malfunction but I don't no how check it.
Somebody have a idea for  my damned problems....

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