Have a 05 dodge 3500 dually with 5.9 cummins. Pretty sure I got more water than diesel last time I filled up. Total loss of power. Idles poorly and shakes. Power steering not working properly because of it. Changed fuel filter but no improvement yet. Can stand on accelerator and it takes almost two miles to reach 100k (60mph). Barely makes it up a hill and loses a great deal of speed by the time I get to the top. Acts like it is trying to stall when I slow down to stop. Not blowing smoke that I noticed just shakes in idle and almost nothing when I accelerate. Engine light is on. Saw something on another thread about limp mode. What is that? Occasionally acts like normal but only intermittently at best. Any help would be greatly appreciated. Not very mechanically inclined. Happened once before from same fuel station around six months ago. Put lots of fuel conditioner in and it seemed to help then so I did it again but so far it has not improved

 

You should drain everything out of the fuel tank, and fuel with fresh fuel. Plus you may need to start filling from a different gas station.
I would remove the fuel filter and install a new one again,and run fuel conditioner again.
As for limp mode, what that basicaly does. When the ecu for the motor detects something in the motor than can seriously damage it the computer will send a signal that will cut the power to the motor.Basicaly only giving you enough power to limp it home or to a shop.
Have you put a scanner on your truck yet??