What would cause my 300sdl to idle rough white to bluish smoke mostly when engine is cold has no blowy performance is great going down the highway it just shakes at idlei all cylinders are working?

What would cause my 300sdl to idle rough white to bluish smoke mostly when engine is cold has no blowy performance is great going down the highway it just shakes at idlei all cylinders are working?
Do a diesel purge, the smoke is when it's cold, but the diesel purge will clean it up and really smooth out the idle, the rough idle is when it can't get enough fuel because the injectors are dirty.