Google KDP on a 12 valve Cummins.

You need to get this done asap if you hasn't been done or you haven't done it yet!!!!!

I also agree with Knoke77 about the AFE air filter. Get rid of the K&N.

I had a 96 12 valve. I loved the engine, the rest of the truck is what I had a problem with. The brakes (issues)and mostly the POS transmission. If it would have been a manual trans, i probably would still own that truck. I had huge power and just broke stuff with it. I went through 3 trans with high dollar stuff in them. It was one too many and now I drive a Duramax.

I spent thousands on that truck, wish I would have saved my money!

Good luck!