I had an issue the other day, but it worked out

fuel tank was almost empty, started truck up in morning, and it was naking a loud knocking noise. I pulled out of the driveway and it was misiing and almost died. I turned around, and went home. I let it idle a bit and it got a little better, but was still knocking loudly. I added a bottle of diesel kleen and filled up the tank. after about 3 miles it stopeed and sounds normal

what was it? stuck injector?, air in fuel line?
I sometimes hear a faint knock at idle

 

You were running out of fuel and had air in the line. If you have not done any fuel mods, consider them, and try not to let the truck get below a 1/4 tank until you have. It will run kinda loud now until all the air is out. Probably smoked some too eh?