yeah, it sounds like the ECU doesn't know that the engine has warmed up. The amount of fuel is different bewteen a hot engine and a cold one. if it tried to idle and then dies, then it is probably the coolant sensor.
the o2 sensor could be causing an issue too, if it isn't reading correctly then your ECU will tweak and try to compensate for it.
and just to eleminate the possibility, hows your fuel pump? and fuel filter?