I have a 2006 f150 5.4 with 118,000 miles on it and it recently started making a knocking noice when its cold. It only knocks for about 1 second and its only when the truck sits for more than a few hours and when im driving and it shifts into 4th gear its knocks real bad. At first i thought the timming chain was going out but the more i read on it the less i think thats whats wrong. People keep saying the timming chain should last that life of the truck but i was wondering if anyone else has had this problem or knows what to do.