May be your competitors having more quality links than yours. It's signing that the site need more quality backlinks and update the content with balancing the keyword density.
I have been stuck on page 3 hit by keyword filter. Previously my site was on page one for the major keyword. I sent reconsideration request, still waiting.
Try some strategies. Like create blog within your website, update it daily with quality content. Perform competitors' analysis and try to acquire links on websites/blogs/forums/articles where they already have. In short, increase number of quality back links.
I had that issue many times to be honest... i just kept building backlinks and they started popping up on page 1 after some tÃme!
Well if you are stuck on page two you just need to do better SEO and get more links for yourself - and give it time. If you are stuck on page two you most likely need more relevant and more powerful links - this can be done quickly by simply buying a couple links from some people in your niche.
Create good content, set up a nice linking structure on your site, and get some backlinks from good high PR sources.
Research your competitors and see what they are doing and then do more than they are. That is the only way you are going to get above them.
Getting better ranking is easy but getting top ranking is very hard. You can get on second/third page by doing hard work and better SEO but to have top rank on first page is most difficult part and you really need expertise in link building, SEO etc.. IMO, maintaining ranking is most vital and difficult task.