My commercial real estate web site (Office Space NYC / Manhattan Office Space | Metro Manhattan Office Space) allows visitors to search for office space listings. It sources listings through a 3rd party and they get displayed in an i-frame. The i-frame directs visitors to listing pages such as: 11 Broadway, 9th floor

At least 10,000 of these pages back link to my site.

My question is this: Could tens of thousands of alpha numeric URLs linking back to my site be detrimental to Google ranking after the Panda/Penguin updates?

Site traffic dropped from 7,000 per month to about 3,300 after the April Google update. Rewriting content for dozens of pages and adding a blog have only somewhat mitigated the negative effects of Panda/Penguin.

Any downside to removing the third party links, parsing these listings from websites and then displaying them with their own URL, title tag, description tag on my site? Obviously the new URLS would not be alphanumeric.

If these links have not caused the drop in traffic last April, what could be responsible?

Thanks in advance for your opinion!!!

Alan