Help: My initial search traffic has gone away - don't understand why

Hello All,

I have a relatively new site (launched in the beginning fo June), and I'm puzzled by what's going on with organic search traffic. I publish 10-item lists of best selling items in various categories. Each item has a name, a picture, a description and a link, mainly to the amazon product page. On top of these, I write unique and usually keyword optimized title, subtitle, and an introduction. I now have about ~60 lists published.

When I started out with the site, everything seemed to be pretty okay, G discovered and indexed the site all well (it is built in Drupal, and I'm building a sitemap.xml, to make that easier to do), and slowly but steadily traffic started to come: from the very few in the early days, it went up to the ~40 range by mid-June, various keywords, nice rankings, all pretty. Then, unfortunately, my site was defaced (an attack against gazillions of Godaddy accounts), but when it got back up, it performed even better than earlier: topping at 55 visits on June 25, all organic search traffic. Then, on June 28, something happened, and my figures plunged: 53 on June 28, 38 on June 29 and 7 on June 30. And it hasn't come out of the one-digit range ever since.

First, I thought that I "over-optimized" the site (product names as alt tags on images, buy [product name] as title tag on href tags etc.) so I rolled back to an earlier stage, where fewer of these were present - with no success.

Then I was convinced it had to do with site performance, as Drupal can be slow with a complex content type, like these lists. I implemented a rather sophisticated caching two weeks ago, that reduced the download time of my pages to ~300ms, still no improvement in rankings.

Intrestingly, I lost all my high ranking (1st page) keywords. These were moderately competitive ones, like [video games june 2012], [bestseller ps3], [cool t shirt designs], [beach reads], [plus size swimwear] etc. Some 90 first-page keywords, according to the Webmaster Tools. What seems spectacular, is that my search impressions have dipped from 2000 on June 25 to 900 on June 29, and 110 on June 30. It has been in the 100-400 area ever since.

According to Google all of the URLs are submitted in the sitemap are indexed, and when I search the site, these pages show up all ok. Still, the best ranking keyword I had last week was position 110 (11th page!).

I don't really get it, why. I keep publishing new content, so I do have fresh content. The product descriptions are obviously copy/paste, but that's standard procedure for all webstores as well. And the overall content I have on the site (with the introduction and the compliation of the products, as well as the uniquely tagged images) is unique.

I obviously don't have incoming links (other than a few press releases I published, and the links I have put up on my other sites), but I guess that's normal for a completely new site. I was about to start publishing blogger interviews (unique content plus great link-bait), but I want to sort this thing out, before I start doing these, because I don't want to emberrass myself with publishing an interview and no one clicking through...

So, as I said, I'm clompletely clueless... If you could point me in the right direction, that would be much appreciated.

Thanks heaps,
Zsolt

oh, in case if you would want to have a look, the site URL is Bestsellermag.com