Hello everyone. Today while sitting at a traffic light my 2005 F250 6.0 CCSB sputtered then rattled ( like a marble in a can ) then started running rough. It feels like it has a dead cylinder now. I'm going to tear into it Thursday night but was looking for ideas of what it could be. Everything was fine. Running great then all of a sudden it started misfiring then a loud rattle and now it starts and runs like it has a dead cylinder. Any thoughts?