It is normal for a cold engine to idle at a much higer RPM until it warms up. The fuel injection system has an enrichement system that will increase the amount of gas injected when the engine is cold...especially at below-freezing temperatures. To burn that extra gas, more air is allowed to enter the engine and that contributes to the higher idle speed.
Depending upon how cold it is outside, the engine idle should drop down to about 1000-1200 RPM within about a minute and finally drop down to a normal 500-600 rpm idle when the engine is fully warmed.
If your engine continues to idle too fast it could be the IAC or it could also be your thrermostat sticking open. If the thermostat sticks open, it will slow down the warm up time and that wastes gas.
...Rich