Rattling noise
 

i've got a 03 5.9l HO 3500 with 190k miles. when i start it i hear a rattling noise coming from the motor, i've checked all injector lines and connections and they were ok. i cant pinpoint where the noise is coming from but it sounds like something is loose. anyone have the same problem? its just annoying not knowing whats going on. it goes away when it warms up. could it be my valves out of spec? i have no idea and am kinda stumped on this one