Huge drop in pages indexed.

I've been running www.TampaRacing.com for about a month on vBSEO and vBSEO sitemaps. Before installation of both I had around 14,000 indexed pages in google. This had been steady for years. A month after install I only have around 600-800 pages indexed (depending on the day) in google. It seems very stable at this number of pages.

Any ideas on what I can try to get my page count back up in google? I was thinking of dropping the .html on showthread and showpost, and utilizing a trailing / . I was also thinking about not including showpost in my sitemaps. Do you think these are good ideas?

Don't change anything is my recommendation. Most of us have experienced an initial drop and some google fluctuation. Then, google picks up again and things are better than before.