LINCOLN NAVIGATOR IGNITION

I Would Like To Know If I Should Replace The Sparkpugs Due To The Mileage. It Runs Fine, But I Think After 100000 Mi, It Needs To Be Done...

I Have A Friend Who Is A Mechanic Who Works On My Truck. About Seven Months Ago He Gave Me A Tune-up, Replaced The Eight Spark Plugs. In...