I have an 05 duramax, has 80,000 miles on it. I also run an edge tuner. My last two pulls to the racetrack, I have noticed some knocking. Tonight coming home it as worst as I have ever heard it.. I seems to only occur between 1400-1800 rpms when I am doing a slow pull away from a stop with the trailer. Now if I pull away from being aggressive with the throttle I don't hear it. It has been awhile since I put a fuel filter on it so I was going to do that, also I usually run total power in the truck but i ran out a couple of months ago, so I am wondering if that could have something to do with it. So do I need to get it to a shop?

Thanks in advance.