I have an 01 6.6 duramax with 175k miles. I am having what i believe to be a fuel issue. It idles perfect and starts right up every time. Normal driving is fine, holds good rail pressure and drives great. The problem is when i give it heavy acceleration. The truck stumbles. Hesitates if you will, like its not getting enough fuel. The rail pressure drops big time at WOT and the fuel pressure guage bounces like crazy. From 10 to 4. The guage flexuates a little at idle but not bad. Bounces between 10 and 11. I have an airdog hp150 on it. New injectors with about 30,000 miles on them. New fuel filters with less than 300 miles on them. New Air filter and MAS. I do have an EFI live 5 position tune on it. Ive also taken out the spring and ball on the return line on the airdog. I cleaned it and put it back. Seemed to help for about 30 miles then back to what it was doing. Also idk if this has anything to do with this but i think it smokes a little excessively. No white smoke, no haze at idle. Ive taken my truck to 2 different diesel mechanics and neither of them can figure it out. Im literally at a loss for words lol