My blog all keywords positions drop significantly, plz help.

I have own domain name and i use blogger free hosting and i have English blog.I regularly update my blog. In addition, my normal daily visitors are 400-600, (it may various), and 80% visitors come from Google search and 50% of them USA visitors.

My problem is last August 22nd my traffic drop significantly, then i checked, adding my blog articles keywords and also my blog title in Google search box. Then my blog articles not appear on Google's first 50 results. Then i put my blog articles entire title in Google's search box and find result, it also same as before. Previously they appear on Google's first 10 results.

Then i check my blog Webmastertool account if there's any error, then i sow that webmaster warn me my blog contain "Duplicate meta description". I added Meta tag for my template on Blogger that Meta tag use entire blog and articles. So i use "if" command and limited main Meta tag only to Home page. In addition to that i checked Google webmaster verification code still on my template then i had seen there's no webmaster verification code then i again added it.

However Google still not increase my blog keywords positions but Google contentiously index my blog, it’s no matter indexing only thing is drop my keywords positions.

In 20th August my blog daily traffic increased in 900% - 1000% with in 6 hours because of my newly published 3 articles, so that Google reduce my keywords positions because of instant traffic increase?


So how do i again increase my blog keywords positions?