Random Internet Blips Ruining Gaming?

I play some games online casually, primarily League of Legends, and about every second sitting the internet has frequent 'blips' of going down for long enough to make the game have connection issues. I've noticed it is the sending that goes down and if the receiving goes down at all, then it is very quick. (The game still plays and I see everything that is happening but cannot respond. This happens in Rift too the rare time I play it and the even rarer flash games I play). Though I have tried many things to fix this issue, it hasn't truly bothered me that much until recently when I realized I play even less than I normally would out of fear the game session will be ruined by the internet.About half a year ago the internet was in very bad shape. It crashed often and stayed down for a long time. My ISP is Comcast (Or Xfinity...), and it took me many weeks of harassing their customer support (off and on) for them to fix it. Then it ran smoothly for a couple months before it started having these blips.

The details:When it has a blip, before, during, and afterwards (I've sat by the modem to watch it happen), there is no indication of the internet having trouble on the modem indicator lights. Nothing changes, and they flash at about the same rate as normal. The router I have is a Linksys, and nothing seems to change on it either during a blip.I have the games port forwarded. All my firewalls including the windows firewall are off. I have updated my wifi and internet drivers on my computer and am using the firmware recommended to me by my ISP for the router.