In UK and AUS, the site comes up in the top 3rd or 4th position for a keyword. But for the US, it comes up on the 3rd page. Also, does size site affect SERPs? The site ranks well (PR 5) while competitors are only 2 or 3. The only difference is competitor sites are significantly bigger. What's wrong?
Even a PR0 or PR n/a site can outrank high PR site for PageRank is not directly related to search result. On geographical case, maybe either your backlinks are counted by those Google bots from UK and AUS, or the other sites are getting good attention from US Google bots than yours. Try to get as much as good quality backlinks from US based/hosted sites or anything you can think that is belong to US region.
Rankings are based on the popularity of your site. You are clearly more popular to google users in the UK and AUS than in the US. Does that match your content/markets?
Add a few quality back links to websites in the region that you would like to target for organic traffic. Try to remember add a few new links every few weeks or few months. When adding back links to your website, it is best to add links to other pages of your website other than just the homepage. You may want to consider having a few experienced SEO experts evaluate your website for the purposes of recommending improvements to help increase the relevancy of the keywords and keyword phrases that you are targeting. If you would like for me to take a look at your website, I would be happy to see if I can find any room for improvement. Feel free to contact me with the domain name of your website or post it here.
another thing.... the title tags and meta description tags were changed, but somehow they got reverted back to the old versions...how could this happen?
It's easier to rank in local google search engines then what it is on google.com What is the domain extension?