oh one other thing if you smoke on the start up and if it just valve cover gasket and you only had the plugs in for month it probably just let oil in the cylinder when you changed plugs if was a head gasket you would have discoloroed oil or oil in your cooloant one of the two it also could be your valve seats are worn. but highly unlikely the burnt ring idea is also plossible but let me ask you this are seeing a lot of oil coming through your PCV valve is so check air to fule mixture. i had this happen once the air to fule mixture was off causing my cylinders to carbon up and putting to much preasure int he crank case thus letting out a lot of oil through the pcv valve just a thought.
