I find myself running into this almost every night. The writing is solid, but I begin to doubt my ability of finishing it. If this is the story you really, really want to write, push yourself to keep working on it. Don't stress if you cannot make the daily word counts.

What would feel worse? Continuing with it as is, or looking back the 1st of December, wondering what would have happened if you kept working on it? For me, the pain of pushing forward now is a lot better than the guilt I'd feel for axing it too soon to know if it's any good.