Higher than normal idle on 98 Chevy truck with 5.7

[wtd]

For the past two winters my 98 chevy truck with the 5.7L has had a higher than normal idle even after it warms up. It is like it never drops down from the faster idle that it has when you first start it up cold. During the warmer months this does not happen and the idle is normal.

There is no SES light showing. Does anyone know what could be causing this? I would think if it was an idle control sensor that it would do it all of the time, not just when it is cold out.

What is the correct name for the sensor that controls idle on this truck and are there any other sensors that affect the idle? Anything else that I should look at?. The truck runs fine otherwise. Thanks.

Wayne

 

[Trav]

Start by looking at the ECM's coolant temperature sensor.

 

[mechtech2]

Could be the coolant sensor. There is one for the gauge, and one for the computer - check the right one.
Also, the throttle body might be sticking when cold, or the idle air control valve.
Clean both as good maintenance. These have to be right no matter what.

 

[Jjones]

Make sure you do not have a vacuum hose that has rotted and has a hole in it.