I have a 2007 5.3L with AFM. I have a pecking sound coming from engine area. If engine is cold it takes two minutes for the sound to start and it never goes away. I believe if it was a lifter it wouldn't wait for two minutes to start, it would bethere as soon as started and in fact would be worse then. Dealer doesn't have a clue. Blew some smoke about AFM springs. Anybody else experience this problem?