My first piece of advice is pure logic. Get everything organized. Whatever you prefer, but get a good way to get all these ideas sorted, searchable, and on file. If you have a lot of things coming your way, you're going to need a system to get the main points down.
Why do all that? Well, it's because you do just have to commit to some stories friend. I've been there, it can be very hard to stay concentrated. But even the best of us can only manage so many stories at a single time. Right now I'm juggling 5 by rotating them through one chapter at a time, but that's definitely my limit. If more ideas come, I just have to set those aside, and save them for a rainy day.
Self control is key. There's just no way around it. But if you can manage to keep good logs, those passed on ideas don't ha e to go to waste.