Had to go out of town this morning and pick up a pump, and I first noticed it when I was getting back onto the interstate. Wound 1st out, went thru 2nd and 3rd, but when I hit 4th, at about 2500rpm it felt like the truck started de-fueling, I went to 5th, and again at about 26-2700rpm, it did it again, by then I was running with traffic and hit 6th gear. I got bogged down in traffic later down the road, and wanted to see it it'd do it again, and in 4th, and 5th, it felt like it was de-fueling at the same rpm's. Could it be this or maybe the waste gate opening up. It felt like the truck just hit a wall and wouldn't go anymore until I shifted and the rpm's came down. I checked for codes when I got back to the shop this afternoon, but none showed up. I know it'll de-fuel at 32-3300 RPM's bur why at this low.
I only had about 2000# in the bed.