For years, I've been using google to search FR, rather than FR's search feature. All you need to do is search for
search terms site:freerepublic.com
and it will restrict the search to just the specified site.
Use
Google Advanced Search and you can also specify a date, whether to search for individual words or a phrase, where to find the information on the page, and a lot of other things you can use to narrow down your search.