To improve the algorithm, I need more sentence beginnings that I know have a resolution, for analysis. So please let me know of any successes you have.
As robin pointed out here a number of successful sentences can be found at this site.
Can you give us an idea of what kind of output we should expect? I ran your code (with my own starting string "I wish I could write a sentence using") and got lots of stuff like this:
Will I get the full sentence if I wait long enough?
It's certainly an interesting puzzle.