Two domains one website...

[dj4uk]

We did have two domains pointing to our website however as one hasn't been used in some time and the old company name is not used anymore it has been turned off. Also we thought this would remove any chance of duplicate penalties from Google. Both domains have been running for years.

This was about 2 weeks ago and we have experienced really bad problems with Google since. I'm not sure if it is just due to this as I believe a link update took place about the same time.

We were ranked in the top 10 for all keywords but have now plunged to around position 150. I also noticed the old domain is now being listed in the results which it wasn't before - even though if you click the link it fails.

When I check links for both domains the old one returns more but when I go to the pages that have the links to our site they are linking to the new domain. Why is the old domain getting credit for links to the new one?

If the new domain has lost alot of incoming links then this could the reason for the position drop?

Can anyone help me out what to do or do I just sit back and wait for Google to sort it self out?

Cheers

DJ