Engine randomly missing/cutting out rpms drop like its going to stall but then it will run fine for awhile then it randomly will do it again anyone ever have this happen?

Apparently as apart of the cam phaser going bad, this is another side effect. While going up hill, the engine will simply die in hot weather. This is not a good thing when traveling a coal haulage road, and you have coal trucks, or loaded lizard trucks following you. I cannot count how many times I have almost met my creator because of this truck.

They put a meter on it said its misfiring on 1,4,5 plugs one person told me it could be the gas another told me i needed to replace my plugs or could it be something else if it is the gas what do i need to do if its the plug where can i find help on replacing the plug i need a diagram on how to do this is there any place on the internet i can get a diagram on how to replace the plugs i would really appreciate it