Are you sure its not water condensation? What color is the smoke? Does it smell like burning? Could be unburned fuel or coolant. If its really cold out I think engines can run rich on startup. Check your coolant level.
Ford's spec is that the lowest cylinder is within 75% of the highest cylinder. I know the SPI engines had a problem with sticking exhaust valves, so much so that ford redesigned the cylinder head to combat the problem.