I've had trouble with this sort of problem. My solution after crashing and burning quite a lot is to make just a few stories, maybe 2 or 3, and plot out their general story/plot lines. Each chapter I complete I get closer and closer to that goal, it creates a positive feedback loop.
You can be a plotter (story planner) or a pantser (do it as you go), but you have to acknowledge that your story is only one story. Too many times I've just smashed whatever I could into a story or started a new one because I felt like I would lose the spark.
Well if the spark doesn't sit with you for awhile it probably wasn't a good idea.
And your story is more about what it isn't (what makes it unique? What does it not do and what does it do instead) than what it is (because if you reversed this you would just spend all your energy making a super book that could never exist due to the sheer time and energy needed to make it.)
It also helps to have a general theme and story to help guide you through this process
So feel free to experiment, but place some limitations on yourself and you'll relive yourself of a heavy load.
For example if you have two buckets of water and you try carrying both you'll probably drop them, but if you take your time carrying them separately you'll get them where they need to go safely.
Just some advice I wish I could have given myself ;)
