The most obvious thing to think is that you're a victim of the fake files that are throughout the network these days. Do the files you're trying to download get stuck at 'connecting' for ages before going to 'need more sources'?
Stay away from files with huge numbers of sources, go for files with 10 sources or less, or even files with a single modem source. Vary your search terms. For music, look for artist or album rather than song title. Also try the All Types search. For video, look up the file before download with Bitzi
How to use Bitzi
Files with lots of sources but no Bitzi rating are often fakes.

You could try deleting LW's preferences folder (when LW's closed). This will kill all your settings within tools > options, you'll have to go back through & reset things afterwards. See points 2 & 3 in the thread below for instructions
Fixes for LimeWire

Your connection sounds fine - you're turbocharged, not firewalled & other users are uploading!
It's a good idea to delete that preferences folder after updating, so see if that makes any difference to things