let me first start of by saying i have a 1996, 3500, 4x4, manual, dually with the fuel plate removed and some pump and afc tuning. I have not gotten around to doing anything with the turbo/timing, or anything like that yet, pretty much all stock other than the plate and afc. I had recently replaced the fuel lift pump on the side of the engine because it was pissing out of the weep hole, and removed the pointless fuel heater. Truck ran great for a few days but just recently started to have power loss at higher rpms. This is what the truck does, when shifting through the gears going from 3rd to 4th, 4th to 5th, and in 5th gear itself, it will start to blow white smoke and sputter around 2300-2500 rpm. the truck still starts up with ease,and idles perfect. when free revving the truck there are no problems, it will go up to 3000 rpms with no smoke at all, once warmed up, its only under load. i does however seem to have a injector either leaking down or sticking. at an idle when cold, you can see a distinctive small puff of white/gray smoke and hear it a little bit in the exhaust, but once it warms up it goes away. the truck has done this since i have bought it about a year ago now. i do not as of yet have a fuel gauge in it yet. but it seems to me that it is losing fuel pressure, or sucking in air somewhere. I checked all the hoses thinking that maybe a clamp was loose or it had cracked or something, but everything appears normal. i have been wanting to put new injectors in it but idk if that will fix it, or if its a good idea to do in case its a fuel pressure, or worse a injection pump problem. i have a few ideas about what to do but want to get some input before getting into it and just pick some of your guys brains to maybe get my truck running right again without damaging anything, or wasting time. any insight would be greatly appreciated!