pull the egr and clean it. if the problem is fixed it will go away after a couple restarts. you can also pull the battery negative terminal and leave it disconnected for 5 minutes (cycle the key after disconnecting the battery, helps reset the ecm by making sure there is no current in the system). if you go the terminal route, be sure and do this on a cold motor. the ecm learns the idle control curve this way and and needs to go from cold to hot in order to do this properly. Also, you need to let the truck run for 20 minutes.