CodyW

Hello and please help me figure out whats wrong, my truck recently threw a code for misfire cylinder 8 at first 1000 revs, so i changed the plugs and put a new coil on that cylinder still had a miss to it i took it to the shop they checked out all injectors etc. and reset codes... misfire went away and was running just fine shortly after when left in gear at like a stop light it would start a knocking sound when i turn the truck off or rev it up it will go away as it happens randomly. so i pulled more codes retarded timeing on bank 1 so i put a new VCT sensor. still having the same problem yet to pull new codes going to replace the other VCT sensor tommorrow any ideas of what it could be ? why a random knock? ps recent oil changes show no signs of metal shavings