one more option,the trottle body might be gummed up.simple an easy fix,plus inexpensive place to start.take the air cleaner off.grab the throttle linkage twist it open.if it looks cruddy,take it off,get a couple can of carburator cleanr spray.spray the holy crap out of it,use raggs to wipe the crudiness away.take the idle air controller off,back of the trottle body,looks like a little sensor,push the stem in,see,if it springs back out,clean it good with carb cleaner and a rag.and on that,make sure the little oring come out with it,if not,get it out of the trottle body,n put it back on the idle air controller before re installing it into the throttle body.hope this helps.and to everyone who reads this, i suggest doing this atleast once a year.it helps.as long as u r careful not to rip the gasket under the throttl body when removing it,its like a 5 dollar preventative maintenance job.

 

It's definitely the idle air controller valve. My truck had the same exact problem. They tend to get gummed up pretty bad. A little carb cleaner and a toothbrush will do ya.