[a.graham52]

its possible. HOWEVER if your car did NOT have a missfire prior to plugs, but it does now... i would tripple check your shit. hate to spend money (like i did with a $400 dollar carb for a $2.50 mistake)on something you dont need. see if you can get your hands on a scantool. or know somone that has one that can show you exactly what cylinders missing (missfire data) that will aid in your diagnosis if nothing turns up after checking your work.