Google Custom Search Results include wrong content

I’m running a site with around 5000 post. Thus searching is a big issue. I frustrated with all search plugins (see previous post), can’T afford yolink and ended up with google custom search. I sucessfully made it working on my page.

But the search no included lots of post, which haven’t to do anything with the post. Google Search includes widget content, menu content and also related posts plugin content into the site. So let’s say someone looks for “abc”. Because “abc” is found in the menu which links to 128 categories, or abc is in the youtube video on the sidebar or abc is found in the footer at the related posts, google links this page in their results. What is the reason for it? Is caching the problem? But I don’t want to turn off Total Cache. Any idea?