Is there a way to automatically stop following a question after x-days? Also, what about a way to manually stop following many items at once? Or only follow a few selected items?

To the right of the question you can just click stop following. You can do it when you click activity for you and see the list of what you are following, or on the question page itself. See on this page it says stop following to the right of your question.

Welcome to fluther :).

As of now there is no way to stop following multiple posts. You have to click each one manually.
Welcome to Fluther.

Like the others have said, it’s just one at a time for now. I doubt anything for that will change in the near future. It actually doesn’t get to be too bad because most of the conversations tend to die off after a few days anyway. Once in a while, an old question will pop up in my activity for you, but that doesn’t happen to often.

There had been discussion of making it easier to check multiple posts off but that was about the time the Fluther team fled.
I guess it fell by the wayside.

There isn’t a way to stop following all at once, but there is a way to remove all of your “Activity for You” all at once. Once you’re on the AFY page, there’s a link at the top right that says “Mark All Read”. That gets rid of all of it at once.

I hardly ever stop following a question, unless there’s a pretty compelling reason. It’s usually fairly manageable, unless you’re away from the site for a week or something.

Don’t get too carried away. Sometimes is worth it to keep folloing something. I just started stop following things the otehr day when my activity was in the 30s. I’m stil following a lot of questions, though. It doesn’t really matter, becfause most of them are dead. Unfortunately, most threads have a short lifespan here on Fluther :(.