I have a 2008 Ram with a 5.7 Hemi. For some time now on a very random basis, when I start the truck cold it may run rough, throw a P0300 or P0307 code and have a noticeable knock or clunking sound. Knock or clunk is not a steady one either. It's very random. The noise will go away and truck runs awesome after it runs for a few minutes or simply by shutting truck off and restarting it. Doesn't do it everyday. Sometimes it's fine for a week at a time or it may do it every time you start it. But only when it's cold after sitting for quite awhile.
All plugs were replaced with OEM plugs right before I bought the truck. I have changed the plugs and cool pack for cyl 7. Have also changed the EGR valve.
Any suggestions??? Don't want to take to dealership to have them experiment with it at my expense.

 

Check coil wiring. Injector wiring. The connectors are supposed to be weather tight. If water or condensation is getting inside, could cause corrosion or short. Or critters may have partially chewed a wire.