cylinder 1 misfire

What is your question?

Hello: Van runs great most times. Intermittently it boggs down, like it doesn't want to move. It does this sometimes during start-ups too! It just sits there and spits and sputters. It's not a good thing when you're on the road traveling. I have to put on the flashers until each episode passes. Even with the accelerator all the way down it just sputters during one of these very unpredictable experiences. what would cause this. Thanks Don