I have a 2001 2500 4x4 with the V10 and 70k miles. I keep the oil changed etc. but decided to change the plugs. I usually buy NGK plugs for other vehicles and picked up a new set. I believe the plugs in the truck were the original (Dad owned since new, I bought it about 8 years ago). I had some stuff to do today so I changed the right side only (5). I drove and noticed if I gave it more than the usual like 40-50 percent I had a ton of valve clatter (pretty sure predet). The plugs I pulled (champions) were showing their age when I pulled them. I noticed the gap on those plugs were easily .060 or greater. My gap checker went to .040 and there was PLENTY of gap left. The forums and parts store all said .045. I have them at .045. The valve clatter is bad and it is definitely affecting power until you get above say 3500 then no knock. IDK, what the heck. Anyone went through this?

 

Did you buy copper NGK plugs or the higher end style plugs? Also, you should change all 10 plugs in the motor before driving it, especially since the old plugs in the motor are so worn out.