Yahoo Updating in a weird way

Rankings go up and down, thus returning sites to old titles and info

[Spelunker]

When I change a title or content to a site, Yahoo updates the information, and the site may increase the rankings because of the optimization.

The strange thing about this, is that after Yahoo has updated my site information, let's say a day after, my rankings drop again because Yahoo returns the information of my site to the old one?

As anyone as the same experience?