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You have a few options you could do. One thing I would look into is maybe doing some url rewriting to change

contactus.aspx?propid=200

to

contactus/propid/200

look at http://msdn.microsoft.com/en-us/library/ms972974.aspx on how to do that for IIS.

A better option I think if you need to keep the parameters the way they are is to use the rel canocial tag look at moz article

http://moz.com/blog/rel-confused-answers-to-your-rel-canonical-questions

but basicly you would need to add something like this to your contact.aspx page(replace example.com with your website url)

This suggest to the website crawler, like google or moz crawler, that those pages should be assoicated with the contact.aspx page.

Just wanted to update this, it took a month but since I decided to completely remove canonical tags and try and handle duplicate content with url rewrites and 301 redirects and I now have 114 out of 149 indexed from my sitemap which is much better. it ended up to dropping to 5 out of 149 at one point.

I may have found the issue today. Most of the articles are pulled from a database and I think I placed a wrong canonical tag on the page which screwed up everything. Does anyone know how long it takes  before a fix like this will show?

Thats a good catch, I fixed that. I do use that in WMT and it has been fine for the longest time.  I guess its not that big of an issue, my main concern was the pages being indexed. Was reading another Q&A thing and used the info: qualifer to check some of the pages and all the ones I checked are indexed and its more then the 11. I just don't understand why its dropped all a sudden, and if that number really means anything.

mmx7719

Thanks for checking, I haven't found anything yet.The site is goautohub.com. it's a custom site and the site map file is auto generated. It's goautohub.com/sitemap.php. I've done it like that for over a year. I did start seeing an error message about high response times and I've been working on improving that. It makes since because we have been advertising more to get the site seen. In regards to the rest of Williams points I have checked those but no improvement yet. Thank you

About a month ago I noticed my pages indexed from my sitemap are dropping.There are 134 pages in my sitemap and only 11 are indexed. It used to be 117 pages and just died off quickly. I still seem to be getting consistant search traffic but I'm just not sure whats causing this. There are no warnings or manual actions required in GWT that I can find.

ahrefs.com is another one, I think that finds backlinks a little faster. I generally check ahrefs, majestic seo, and OSE.

You should also look at submitting a sitemap (https://support.google.com/webmasters/answer/156184?hl=en) so you setup your site to be organized.