I wanted to provide an update from my post on Oct. 28th. I had 6 sites all drop off the face of the earth. i.e. from spots 4,5, for one key word, 6 from another and 2 to spots like 506! As of yesterday morning they were back. I found out that a few of my high PR backlinks that I was using consistently throughout all my pages went away. The website owner dropped off the spam pages, which in turn discounted several backlinks with a lot of link-juice.
The good part is, I never stopped building backlinks so a few days later, Google found my new backlinks and I'm back fighting for the top spot. I never removed Google Analytics.
I hope that helps.
-Capp