realmaverick - 12:26 am on Apr 24, 2012 (gmt 0)
Hi Whatson, you best bet would be to post your URL over at the google forums. That way you'll be able to get much more customised advice.
Ultimately, it's very hard to know what the culprit is. Ads are only an issue, when they are excessive and dominate above the fold. Of course, that's only a rule of thumb.