Code po3044? Causing blue white smoke?

[boatwrks]

I just bought a 03 lb7 in decent shape it has a rough idle once in while and smokes at intersections on and off. I took it to a local diesel shop had the truck red the only code that came up was the po3044 I was told it was cylinder 4 miss fire all the balance rates were with in spec he said they cleared the code and told me to come back in a couple days to check again. what dose it look it might be?