Have you reset the PCM in the car?
Disconnect the negative cable for 5 minutes and then connect and restart.
Gotta be 5 minutes, no less.
If it continues, it sounds like the IAC Valve may be sticking when cold.

Pete...

98.5 SE Sport Duratec ATX (P66L)
Black Clearcoat on Greystone
DOB 11/21/1997
DOP 12/25/1997
PIAA 510 Super White Driving Lights
SVT CAT-BACK EXHAUST (No Resonator)
DiabloSport Chip (LPQ4) - Engineered To Raise Hell
Too many other mods to list...
Sounds sweet, runs quick...
Crazy Horse Dyno @ 121.4 WHP/129.6 TQ