Engine Performance problem
2005 Ford F350 6 cyl Four Wheel Drive Automatic 121000 miles

While driving, the engine stalls. When this happens a light comes on that is a gas pump with water droplets on side and then the light that is a small curl comes on too. The engine stalls, and after a 5-10 second wait, the lights go out and the engine picks up fuel again. There is a (water bulb) on the engine, but when checked it is full of Diesel not water.
We have taken it to the shop and was told we had water in the fuel and ti use additive, due to low sulfur content in the diesel. We do but this still happens. What now.