Does google place sites for certain keywords the same time they do pagerank? I have a page rank 3, yet my keywords are not coming up in the search engine?

No, chasing Pagerank won't get you rankings. Look for quality links from related sites rather than those with high PR.

Keyword rankings can fluctuate daily now, which never was the case a few years ago. I agree Matt, focus on links and on creating content that addresses the needs of your potential customers and prospects.