I have an 01 e350 super duty with the 5.4 in it. Took it to the shop to have spark plugs changed, went to pick it up and the guy tells me he could only change three plugs! He says the other five have so much rust that he cannot get his socket on the spark plugs. Say the rust is built on the walls going down into the spark plug hole, he says he tried running a screwdriver and a couple other tools down inside there trying to knock the rust down and that he had no luck. Anybody heard of this? Any idea of what I should do? Seems like at this point once these spark plugs are done so is the engine?