Since viewing this site off and on, am glad for the wide range of imput. Was quite concerned with so much info on Piston Slap. My 1999 5.4l build date 9-29-98, will be going into the dealer tomorrow for diagnosis of noise. Am concerned of the outcome. I am looking for as much info that I can arm myself with in order to make sure everything is done correctly. If I don't feel good about this dealers findings, am prepared to pursue another one. anyone's help would be appreciated.