Change Website Content = Risk Google Ranking?

Hello everyone. Long time reader, first time poster.

I work for an online shopping mall for the gourmet products and specialty foods industry, www.gourmetfoodmall.com. Most of last year, we were ranked between #4 and #10 on Google for the search term gourmet food. We were dropped out of the rankings alltogether at the time of the November (Florida?) update. We started to crawl back up in the rankings shortly after Christmas, finally settling back between #4 and #10. With the most recent Google update, we have been placed at the #1 position in the SERPs for gourmet food, finally overcoming the usual #1 website, Epicurious (who have a large number of pages in their URL, as well as over 7,000 incoming links).

On the other hand, our Yahoo ranking is very poor. We are currently ranked #56 for the term gourmet food. I am aware of the fact that Yahoo has started to implement their new algorithm, but we have not made any changes to our site to correspond with this new algorithm.

My question is this: Can someone with knowledge of both the Google and the Yahoo algorithms and SEO requirements please take a look through www.gourmetfoodmall.com, and give me any recommendations you may have on what we should modify in order to comply with the new Yahoo? I am afraid of changing much on the site, for fear of losing our current #1 ranking in Google. Any other comments would be greatly appreciated as well.

By the way, we are currently positioned at #10 in HotBot for gourmet food. I believe that we submitted our site to the free Inktomi site submission program, but I know for a fact that we did not sign up for Search Submit with Inktomi.