My theory is that the coolant temp sensor is sending a low resistance to the
ECU. The ECU thinks it's hot (but actually cold engine) so it puts out non-rich
mixture. This is indicated by the erratic idling on a cold engine sitting
longer than 2 hours. To override this function just unplug this sensor
connector then crank the motor. Watch how it runs. (The intake temp, throttle
sensors, etc also plays a role in fuel mixture.)

Second theory. The cylinders or cylinder is/are experiencing a flood. This is
indicated by the erratic idling then clears up. To eliminate fuel or clear up
fuel, unplug main relay fuse (ECU or fuel pump) and crank for 10 seconds.
Rumors (in my tech class) suggests that pressing the gas pedal to the floor or
in certain ways will turn off injectors for the first few seconds of starting.
Worchid