A friend of mine has a 6.0 powerstroke. When he starts it in the morning it fires up real slow. It wont go over 25 mph. It has a terrible miss sounds bad and it white smokes. Any ideas? Kinda clears up later in the day.

Is he running the right oil? If the oil is too thick, he won't get any oil flow through the HPOP to actuate the injectors until it warms up.

Changed the oil. No help. Does it when its warm sometimes. If you hold it off idle at about 1500 it sputters and sounds nasty.

He might have a bad injector,The EGR valve might be stuck open, Sensor issue, Bad fuel or a pluged fuel filter. Any one of these can cause what you diescribe. It's hard to say with out seeing it.
Did he fuel up right before this happened?
I'd check the fuel make sure that he did put gas in there by mistake.

Been going for some time now more than five tanks. All new filters. No engine light.

Three main causes of this issue. One is simple the others not so much. Glow plugs is the simple one. Amp-clamp the two bank leads near the glow-plug relay. Turn on the key. They should settle out at or above 40amps each bank. If less - bad plug.

The not-so simple is the injectors or the ECM/IDM programming. They are/were continuously updating ECM/IDM programming for better performance all around. Early builds had horrid cold-start running issues. A simple update solved this instantly without any mechanical changes.

These injectors have a few failure modes. And its common for them to fail in one particularly bad way: the little (I mean LITTLE) bolt that holds the electromagnetic coil at the top of the injector loosens, drops its but into the oil pan, and disables that injector.

I would highly recommend finding a shop that can do and injector kill test or even a simple injector buzz test.