98 Dodge caravan 2.4, engine rpm too high at start-up?

When the vehicle is started in the morning, especially when it is cold, the engine rpm's are excessively high. I replaced the throttle position sensor, but that didnot help. Is there a procedure to adjust the computer program. I have a OBDII tester, but the manuals both dodge and OBDII say nothing about how it is done.