I recently purchased a 2003 f350 6.0 with 102k miles. I noticed today that if im one the interstate and let off and hammer it to the floor itll puff some black smoke. Also when i start it this morning after sitting 8 hours in 32 degree weather, it ran rough for 3 seconds and puffed a little blue smoke in that time. Then i had to move the truck so the ole lady could get out and when i hit the throttle it puffed black? Also noticed a distinct knock when in the drive thru. Am i looking at injectors or something else? Truck is stock as can be. New to 6.0 so any help is great

 

Pull egr valve and see if its stick/clogged replace it or delete it. Any hissing noises under wot?