Frank Kuhl

Hi everybody, 1999 f150 with the 5.4 makes a rattling noise when ever i apply or release throttle. this noise concerns me. it dose not sound good. i was thinking it could be the piston rods, but I'm no mechanic, so i figured i ask the experts. what could this noise be, is it bad for me to drive the truck. what kind of repair do i need and how much would it cost. thank you