I've been ranking on page 1/2 for keyword for a few months now. Lately for some reason my site is result #5, or page 3, or not even in Google at all. I tried Google in the UK, NZ, AU, NG, DE, and all of different results. Some of them I am on page1 and some of them I'm not listed. It really varies from day to day. Is there any reason I keep bouncing around so rapidly in US data centers? Is this normal?
How long has your site been around? Newer sites' rankings tend to fluctuate more than older sites. Google rankings are very dynamic. For the same keyword or keyphrase, you can see different results if you search in the morning and afternoon. It is totally normal to see the ups and downs. In the long run, solid link building and fresh content will help keep your site at the top for an extended period.