My 7.3 has new glow plugs and relay but does not want to start when first thing, when it does it runs amazing. Blows white smoke at first then idles rough until warm, if it sits for a couple of hours does the same thing?

White smoke is a sign of water vapor or fuel that has been atomized, but not burned. Water vapor may be present in the fuel, or water may be leaking into the cylinders from the cooling system. Also, air in the fuel can cause white smoke. White smoke usually occurs when there is not enough heat to burn the fuel. The unburned fuel particles go out the tailpipe and typically produce a rich fuel smell. It's not unusual to see white smoke in the exhaust, during cold weather, until the engine warms up. Bad glow plugs (burned out, coated with carbon, or not receiving proper start-up voltage) or a faulty glow plug control module can cause white smoke on engine start up. Low engine cranking speed may also produce white smoke. If white smoke is visible after the engine has warmed up, the engine may have one or more bad injectors, retarded injection timing, or worn injection pump. Low compression can also be a source of white smoke.