Ok so i bought this car about 6 months ago. I did a tune up on it, Breaks, spark plugs, oil change w/ filter, and belt. When we did that tune up (1 month after i got car) The first two cylinders had oil in them. Well we ddnt do anything about it and now the car sounds like its backfire, it sounds like a loud go kart, the car shakes from what i believe and the cylinders misfireing and idk if this is just a bad valve cover, or a head gasket...or both??? What do you think? We havent chked spark plugs again to see if coolent is in in there too now, but when we did tune up it was only just oil.