Last night on the way to dinner with the wife, I noticed that when stoped at a stoplight, the RPM's surged from 600-900RPM. It happened on the way there and again on the way home. I have an '06 4.4 w/ 23K on the clock. Before I take it to the dealer so they can sit on it a week,only to tell me all is normal, does anybody have any ideas as to what this might be? It was 30 degrees out last night here in SoCal, but I have never noticed it before when we go to the mountain where it is just as cold.