Should there be a time limit for old questions from users with very low reputation? It seems that some of the stale questions are from users that will never return. Perhaps there should be a limit set to the number of days that a question asked by a first-timer will remain before it is automatically flagged or removed.
This already happens, but it's not based on the reputation of the user: it's based on the score (votes) of the question, the number of views, and a couple of other things. Questions with helpful answers also won't be deleted.
The network-wide meta site has a description of when questions get automatically deleted. The system is known as Roomba.