Person i brought mine from filled it up to much.... Had the same problem with oil in the airbox, and tubing, plus up in the inlet manifold. Oil pressure light used to come on, engine used to accerate uneven, like it was cutting out.. really weird.. Anyways, i did an oil flush, and put new oil in to correct level, and cleaned the air filter, tubing, throttle body and inlet manifold as best i could.
It was fine then!
Knobby.