I don't know that it's just you or your search. I've had the similar experience of using a search that resulted in a flood of "hits" that came back empty (or nearly so) when I used one of the Advanced modes to limit the search. Like you I've tried to limit returns by date (major failure). Also have had problems searching in subject (and got no returns even if I'd just seen the word in a posted subject line). Weird search engine.
FWIW, I've actually had better luck using that g**le search beast. It will often take me to the exact thread I was looking for; often the exact post. I am, of course, very familiar with that search engine.
Cheers, Ed