Salutations my friends! I request urgent help, as the status of my internet renders me very irritated and unproductive. Any help would be GREATLY appreciated!

Thanks in advance!
Heres my problem: my internet is constantly slow, randomly a page will load fast, but then when I click on another link, it will be stuck at the loading screen forever.
Also with instant messaging programs such as AIM and Xfire, I get disconnected every 1-2 minutes, and I can barely keep a conversation without it getting disconnected. Usually, I can immediately re-log back on sucessfully after being disconnected. When I do get disconnected, my task bar does not show the normal disconnection icon, in fact, it doesn't show anything at all. I'm guessing my computer cannot detect the disconnect because it is maybe a split second disconnect, or a partial disconnect. (Maybe some ports are acting weird?)
I have accessed my router and turned on DMZ, turned off NAT, and any firewalls. I have done a full virus scan. I went to a Port Sniffer website, and it could not access my ports; it timed out when it tried to check my ports. (Thats weird.) My ports have all been open and been able to be accessed before.
Also, on Counter-Strike: Source, I cannot get a full list of servers. When I try to retrieve the server list, I get maybe 20-30 servers at most. Even if I join one of those servers with 20 ping, it is unplayable because of lag. (This has happened last year, but I fixed it by opening my ports with DMZ.) Now it happened even with DMZ!
I noticed this started happening after I used a p2p program Azureus. I have used Azureus before, for a while, but this kind of thing never happened before. The internet lag used to only happen when Azureus was running, but now I uninstalled it and no longer use it. Even so, the internet still lags and I constantly get disconnects on my instant messengers.
Summery:
Problem: Slow, laggy internet. Instant Messengers constantly disconnect.
Suspect: Closed ports? (But my DMZ is on!)
Attempts at fixing: Turned on DMZ, turned off NAT, turned off anything that could possibly get in the way of ports, did a full virus scan.