I have a 2004 5.4 Triton F-150 runs good and when it gets warm the passenger side valve cover starts to make a rattling noise,any help would be great,and it is like it starts miss firing also when warm

 

Sounds like maybe a rocker arm is out of adjustment. Also 5.4's coils are known for failure but is usually very noticable vibration and power loss. The valve cover is fairly easy to remove. Maybe get the engine warm and let sit for a couple a minutes to let oil settle. Then remove valve cover look for anything suspicious. Also maybe use a stethoscope to pin point noise.