Hi-reving when not in gear, and not pressing the gas?????

[clariveros]

Any help would be good...
I have a 2001 GMC Jimmy 2 door, it has a manual transmission.
and since it has been getting cold here (up north), in the mornings the engine revs up to 3000 rpm when not in gear usually while driving. i note this problem when i am stopping at a red light...I changed the air filter and most likely have to change the fuel filter, but could it be anything else be the problem?

[BlazerLT]

Clean and reinstall your IAC valve.

Clean with throttle body cleaner and a toothbrush. also clean the hole it is installed into.

[medic6]

check for a broken vacume line possible line to pcv valve or at least a major size vacume line.