Spluttering engine

[cornishberlingo]

Hi All

A few weeks ago i was driving my van into town and all of a sudden it spluttered and coughed quite a bit like a old damp BL engine.

It lost all of its power basically and ran a bit lumpy, if i tried to give it stick it smoked dark/light blue which is oil.

I then turned the engine off, let it cool then all is good again.

Now and again i do get some misfires. Temp is good, newish fuel filter and newish air filter.

Has anyone had this happen to them?

Thanks
Adam