I had the same issue before. The problem with mine was a injector that was always firing or not firing in time with the spark. Mine occured after I had the engine out and put it back in. The actual cause of the problem was a loose wiring harness. Basically the three wiring harnesses on the passenger side of the engine compartment were not "clicked" together. Un-plug those three harnesses and plug them together. If you do not hear the click when you put them together than they will not make proper contact. 2 of mine clicked and the third required a pair of channel locks to get it to click. Once I did that the misfire was gone and no more gas in the oil.
