Have a 2006 f 250 blowing white smoke get up tp 50 and smoke quits below 50 and its like i have a fog machine ???????

depending on smoke ---white = coolant or water being burnt /head gasket intake gasket blown cracked or damaged head cylinder ////blue burning oil /// black needs tune up or fuel supply problem

Blow head gasket. Just did one today.

nno
it is water vapour caused by the steam from combustion and condensing in a cold exhaust system
the reason it goes away is the whole system gets hot and you don't see the "fog" of the condensation
It is the same effect as your breath leaves "fog" from your mouth on cold mornings

You don't mention what that smell is reminiscent of?

You don't mention the colour of the "smoke" and you didn't say whether the engine is petrol or diesel?

You don't mention whether the road behaviour/performance is normal?

White smoke is almost always steam or in the case of a diesel it could be an unburned fuel mist, grey/black is excess fuel and blue or grey/blue is burning oil.

Some steam is fairly normal until the engine and exhaust system is hot but excessive amounts could be one symptom of head gasket trouble. If the engine is drinking coolant and sending it through the exhaust as steam it will sometimes smell spicy.

Burning oil smells a bit like burned eggs in the frying pan.

If the car hasn't ultra-low sulphur oil and fuel the catalytic converter will convert sulphur traces into hydrogen sulphide - the bad egg gas...

you my have thick smoke coming out of your tail pipe or oil leaking out on to your engine

There are few possibilities that can cause such problem.
I recommend you few help links related to your problem.Click the link below and follow the troubleshooting;-----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------
Brake pedal stuck? http://howtobyme.blogspot.in/2012/03/brake-pedal-stuck.html

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Car only starts when gas pedal is pressed? http://technoanswers.blogspot.com/2012/01/car-only-starts-when-gas-pedal-is.html

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Car won't start without hitting the gas pedal? http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-without-hitting-gas.html

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emits whitish bluish smoke and bad fuel smell from exhaust

http://schematicsdiagram.blogspot.com/2011/12/van-emits-whitish-bluish-smoke-and-bad.html

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White smoke and Acrid Smell? http://whoisbyme.blogspot.in/2012/07/white-smoke-and-acrid-smell.html
---------- Car stalls and throws white smoke from exhaust? http://repairhelpcenter.blogspot.com/2012/01/car-stalls-and-throws-white-smoke-from.html

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This will help.
Thanks.

Quit driving it. You have blown a intake manifold gasket or a head gasket. 3.4 engines are known for blowing intake gaskets. Check your oil, make sure it is not exessive or milky in color. White smoke is caused from water/coolant entering the cylinder.

black smoke is fuel white smoke is oil. change your spark plugs to a hotter plug and run with some hpr 50 engine oil or somrthing nice and thick

It's just condensation. Water will also drip from the pipe.

The colder it is, the worse the 'smoke' will be. I was in Vernal, Utah earlier this week, drove through -18*F weather, my truck never quit blowing white smoke.

And NO IT IS NOT YOUR HEADGASKET

well, it will cause sludge in your fuel system, you will have to have it clean before it fails on you.