The 'Write' Stuff?

The nagging doubts, the second-guessing...is this normal for an author?  I have no doubt that other writers must feel this way after finishing a book and moving into the editing phase.  That's where I find myself now, and I'm not a fan of it.  It's not befitting.  This business requires a certain confidence - perhaps even bordering on cockiness, if you're going to succeed. 

I know I'm a good writer, yet as I slash away, removing unnecessary words and adding others, I'm starting to wonder.  It's an odd malaise that I'm sure will pass, but I don't have to like it.