joy:

i noticed a number of posts sugesting that the coolant #2 sensor may be at
fault. not likely, but symptom of easy cold start and subsequent
difficulty starting warm/hot could be explained by disconnected #2 sensor.
essentially, the resistance of the sensor tells the computer the
temperature: in ohms, roughly 250 operating temp, 2000 room temp, several
thousand below freezing. so the ecu treats a disconnected sensor, infinity
ohms, as reporting very cold temps, and she starts just fine cold, but
not, subsequently, hot. badly corroded sensor/connector contacts, or a
broken wire, might produce similar symptoms. checking for voltage at the
connector, and measuring sensor resistances at various temps, is very easy
with a multi-meter.

dan