My current writing project is an excellent example of an idea in search of a story.  I finished a story that flowed quickly and felt easy.  Then I had an idea for another story and started in on it.  Then I realized that the idea didn't have the sticking power in my mind and it drifted for a month or so with no progress.

The issue is that an idea doesn't always mean you're ready to start.  I should have recognized that I didn't have defined characters, didn't have a plot beyond "get to the top of the tower and fight", and I didn't have a resolution or even a hook that needed resolving.  Therefore, it should be no surprise that the momentum faltered.

But now things are starting to gel and I have a vision for the characters, their relationship to each other, and how to bring this to a satisfying conclusion.  Of course, the first sections are going to need complete revision but that's all part of the deal.  This one should be done before the end of the year.