6.2l please help will not run
 

Hi there so I recently acquired a 6.2l c10. The previous owner had had it sitting in a garage for a few years with half a tank of fuel. The truck drove for about 600km before it stalled on me on the way to work, I then had it towed to a shop. The mechanic was able to get it running by I believe cleaning the fuel pump(has an inline pump installed).I was able to drive the truck another 200km before it did the same thing luckily this time I made it home. I decided to drop the tank and found that it was sludge and rust, at that point I ordered a new tank, fuel sending unit and both secondary and primary filters. After installing all that the truck ran and idled but idle was super rough I figured I was picking up air, I replaced the lines on top of the tank, cracked all injectors and turned over even tried finding any leaks by pressurizing the system through the return line on a tutorial I found on this site. The truck will fire but only run extremely rough for about 10 seconds on or off the gas(on gas it will rev up and die faster) and there is a ton of white smoke. I'm running out of ideas here and I can't find much more information . If anyone has a.suggestion or can point me to the right post I'd greatly appreciate it.