Awful Internet Speeds in Arizona. What's causing it and how do I fix it?

I pay for gigablast and I've been having EXTREME issues with my speeds in Chandler since I moved here from Tempe about a month ago. 

Typically I get download around 150mbps and upload around 25mpbs. Randomly throughout the day (like 7 or 8 times) my internet will drop down to 1-2 download, and <1 upload and persists until I unplug the modem. This fixes the issue for an hour or two until it happens again. I work from home, and having the internet constantly cut out when I'm in video conferences or completing urgent work within my company's systems is less than ideal for my career health.

I contacted cox and they unhelpfully told me they weren't seeing any sort of issue on their end.

At first I thought the issue might be with the cox panoramic modem/router so I went out and bought an expensive arris sb8200 modem along with a new router. The problem persisted. All that did was increase the speeds I get in between my internet working.

I contacted Cox again who at first tried to tell me it was my modem that was the  problem. I explained that this wasn't the issue and I bought the new modem because of the issue in an attempt to fix it. After many conversations with support, I got a tech to come out to my house. Tech told me the line was bad and replaced it, and went on his way. An hour later, same issue.

I get another tech out to my house who runs tests and tells me everything looks good. He says he will submit a ticket and gives me a ticket number. Says Cox will contact me with an update soon. I talk to an agent today who tells me there is no ticket for my ticket number (lol) The agent today schedules another tech to come out to my house in a couple days. I accept although I don't know why this will be any better than the last two visits. At least this agent didn't try to tell me the problem was my fault.

I feel like this has to be some sort of issue on cox's end? I've already determined that its not my modem or router, and the first tech replaced the line at my house. 

If anyone has any sort of idea what the issue is or how to solve it, I'm all ears.