My 1998 Honda Prelude has trouble starting on very cold mornings. Need diagnostic advice. Engine was recently rebuilt.

. Check/replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. They become corroded, due to not changing the coolant frequently enough.

. Check the Fast Idle Thermo Valve:

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