[Does having your main keyword in the last sentence make much difference as to whether your site gets ranked well or not? I have a site which is about 4-5 months old. For weeks now it hasn’t been anywhere in the top 20 pages on Google for its main keyword and I’m trying to figure out why. A few weeks ago, it was ranked on page 2. Today I noticed that SEO Pressor said the keyword isn’t in the last sentence on the main page, so I added the keyword in the last sentence. Could the site still be doing the Google dance? Someone told me that after a site is a few months old it should no longer be doing the dance.]
It sounds like your page is facing superior competition.
When your page was ranked on page 2 it was most likely benefiting from the temporary boost of QDF. Once that boost wore off it dropped to its’ currently earned position. You need to get busy promoting your page by building high-value backlinks.