New van running rough, smoke

Hi. Has anyone had issues with a new second hand import diesel that may have sat around for a while intermittently running rough in Drive whilst stopped, and occassional puffs of smoke, white and black? Is this "normal" and should it burn off in a few days?

I’ve just fixed my power and smoke issues. Wouldn’t rev past 2900rpm. Total lack of power. Black smoke at full tilt. White smoke under no load and just revving. I don’t want to scare you, but:
Injectors serviced, valve was sticking (shimmed), crack in the alloy intake tube that goes over the top of the engine welded and polished, cylinder head removed and machined. AU$4k. Runs like a dream now. Zero smoke. 3L NA diesel 1996 450000km.
Done now, but worth it in the end. Good luck!

When I bought mine it was lacking in power, 95 km/h was the best it could do, used a bit of oil, and tended to run on slightly when switching off. It was 21 years old but with only a bit over 60,000km on it (if genuine). That suggested that it had only light use in Japan and may be somewhat coked up. I gave it a bottle of injector cleaner and my normal usage gave it some long runs at highway speed. Within a few weeks it had opened up and can cruise happily at 110. Oil consumption also dropped and now, some 150,000km later, it hardly uses a drop.
As I understand it, black smoke indicates excess fuel, white = oil. A new air cleaner may help with fuel.
I would suggest giving it a little time and some highway runs, try what I did, and keep an eye on the oil. Go for more drastic measures if it doesn't appear to be improving.