yahoo geolocation is driving me crazy

[screwingup]

I have a number of sites which have almost the same backlinks. I am ranked extremely well on mx.search.yahoo.com, uk.search.yahoo.com, fr.search.yahoo.com and so on... In the main search I find my sites on the 3rd page and lower. This thing is going on for months. All the domains are hosted in the US on "very old" hosting providers, so it cannot be a nameserver issue (or at least I hope so...)

What should I do to get out of this filter? Any thoughts? Any ideeas?

I imagine it's a backlink problem (I get links from sites hosted outside the US) and (probably) a meta-tag issue.

The MAIN curiosity is that some sites, even hosted on the same server, have good results for some kw on the main Yahoo search and the others are filtered as hell. Backlinks are also almost the same for each one.