Ibought a90 Honda Accord approximately 8 months ago. One previous owner, dealer maintained but it gets poor gas mileage. I do have oil in the spark plugtubes and have been told it needs a valve cover gasket. Could this be the reason I'm getting poor gas mileage and if not do you have any other suggestions?I have checked everything I can think of. Have had the oil and trans fluid changed, air filter , checked tire pressure, car passed emissions test with flying colors and does not smoke. No leaks of any kind.Want to change plugs and wires but want to wait till after valve cover gasket. Any help would be appreciated !

Dan