[GTP Dad]

There are other items that can cause a misfire besides a plug. The wire may also be the culprit or you could have a bad injector. Of course it has to be the hardest one to get to. If I were your husband I would do a compression test on the engine. This will tell you if any valves are stuck open or not and if there are any issues with the head gaskets. If the compression test comes out ok then I would replace the plug wire and the fuel injector to see what happens. What color was the smoke and is it still smoking?