white smelly smoke from tail pipe after stop or slowdown and then accelleration. on 2010 Ford F-250 Super Duty

So the truck has been to the dealership twice by the first owner and me, the second owner for the same problem. White smelly smoke generally happens after I stop and then go or simply slow down and then accellerate. It also happens while just driving along at a steady speed. The dealership said there was no codes on the OBC and to just drive it until it doesn't stop, then they'll know what to fix.
The coolant fluid level is fine, no coolant in the oil either. The first owner had one of the EGR valves replaced, could it be the othe one gone bad now?