I finally fixed this. My nagging problem was that if you used the search_mod.asp page it would never highlight your search terms if you used the "exact phrase". I compared the normal search.asp page with the mod and found the issue.
In search_mod.asp (or if you are already using it you may have renamed it search.asp) on line 394:
SearchLink = "&SearchTerms=" & chkString(strKeyWords,"urlpath")
Change the part in red so it looks like this (shown in green):
SearchLink = "&SearchTerms=" & chkString(strKeyWords,"search")
Now it will highlight if you search for an exact phrase. <