Cannot Fix Internet Issue.. Please Help!?

Greetings, For the past week the internet in the house has been really spiky. We never had problems with it before in the past used to be able to play games just fine and everyone in the family surfing the web and so forth and no bad sign at all. So, we though the modem was bad so we called Comcast they sent out a tech and switched the modem out yesterday. Well.. I'm back to right where I started. I'm currently only getting 1.80 Download and 1.57 Upload speed. We are using a wired modem with built in Wifi. What is causing this? Is it another possible bad modem? Perhaps the router is dying? I'm trying to figure out how to fix this and I'm running out of idea's Thanks!