When it comes time to do a tune up on your 79-93 Foxbody Mustang, spark plugs should always be on the list. Spark plugs are fired by your spark plug wires to ignite your air and fuel inside of your combustion chamber. A fouled or damaged plug could cause your plugs to misfire giving you a rough running engine, sometimes referred to as a "miss". Having a misfiring engine causes poor performance, decreased fuel economy, and sometimes a no start condition. Replace yours today and get your Fox Body running right again at Latemodelrestoration.com.