1996 Buick Skylark 3.1L V6

Several months ago, someone accidently poured about 2 gallons of kerosene into gas tank. I have recently purchased car and need idea's. First, there was a significant amount of gasoline in the oil. Second, we added 3 and a half gallons of fresh gas into tank. It now runs, but rough. It used to smoke bad, but has since cleared up. Any ideas. I have drained the oil and removed the filter. Both which had gas mixed in it. Alot! Was that the reason it was shaking and running rough. Will changing the oil and filter improve preformance? I don't wanna spend any more time or money on this thing. All ideas accepted please