Problems with my ford diesel truck?

I have a 2002 ford f 250 7.3 Diesel, it started missing and I was low in oil. I replenished the oil but it is still missing and blowing white smoke or the muffler. Any ideas as of what can it be?

Well white smoke indicates water in the combustion chamber. I would check the coolant and see if there's any oil in it. And get a pressure test done to see if there's any leak in the cooling system.

Watery/steamy smoke? Head gasket?
Oily smelly fumes. Injection timing off?