Google indexing Post URL but Not content -- NEED ADVICE--

I have a tech related blog. When I publish content on it the URL of new post get indexed but when I copy and search the content of the post my blog doesn't show in results. It is a 2year old blog with 300+ posts. All posts are unique and self written content.

In Google search people who copied my content are ranking but my website even don't show up in top 100. Even those post which were ranking on first page for there keywords don't show up if I search a complete paragraph of the article.

I even got an mail from adsense that Adserving is disabled on the blog.. I am pretty sure it is because they are assuming that I am using the copied content.

I am not sure why this is happening that my original content is not ranking at all..
Please advice me how to solve this issue

Add noindex to the old posts. Search google about last panda update from August 13.

My Suggestions
Make sure you have a good site map for Google to index.
Try using blogsearch.google. com
Also since it sounds like you have good content try out a service called outbrain .com
I'm a PPC Guy so I like to pay for traffic and the prices are not bad.

Good Luck

I had somewhat of a same problem, but in my case it is a vbulletin forum and my posts are getting indexed and not the URL.