I have a 2000 f250 with a 7.3 diesel and when I start it, it has a rough idle and has white smoke coming out of the exhaust that smells like diesel can some one please help

This link should help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1977241

White smoke coming from the exhaust on a diesel is unburnt fuel. Combine that with the rough idle, and that sounds like a bad misfire to me. If it is only on start-up, and more specifically on a cool/cold morning, I would begin investigating glow plugs and the relay that controls them. On a cold engine, if a glow plug doesn't heat up enough/at all, the fuel in that cylinder won't ignite, but as the engine begins to warm up as it runs, there will be enough heat generated to begin the combustion process in that cylinder, and the rough idle/white smoke will go away.