Connection Problem

Alright so I can no longer play CoD4 because when ever I try to play I connect to a 50 ping server and Its just nonstop lag with a constant connection interrupted. I disabled my firewall, reset my router and modem several times and nothing helps. I can play Steam MW3 and BF3 fine no problems but CoD4 always lags. It just started happening recently and I have no clue why. My computer is fine and my internet is fine. I've searched everywhere for an answer and I just can't find one. If anyone can help I will be extremely greatful. I have also tried deleting everything and then re installing but it didn't help at all.