High Latency, Packet Loss, and Slow Speeds

I upgraded to gigabit internet back in June 2019 and have an Arris SB8200 Modem and ASUS AC3100 Router. I used to get 940mbps down and 35mbps up. However, in January 2020 I started experiencing very bad packet loss and latency spikes while gaming. The tech came out and found no issues inside or outside of the house.. however within 1 week of his visit my problems magically went away. Now in March 2020 I am experiencing the same issues again and have changed nothing at my house. My ping will spike from 39ms to >100ms at complete random and I get constant packet loss icons while gaming (5-10%). This has been going on for 2 weeks and my speeds have dropped all the way down to 500mbps down and <10mbps up. Even when I ping or run a tracert to google I am getting pings of 200-300ms and connection time outs. The tech came again this week and replaced the Moca filter outside but the problem still remains. I've tried 2 new routers and 2 new modems, a new coax cable, and multiple known-good ethernet cables to no avail. I am hardwired on a desktop to the router and have even blocked ALL other devices from connecting and the problem remains. I see countless posts on this forum with the same issues and no resolutions. Cox needs to fix this -- I have been a paying customer for 15+ years and they continue to provide terrible service. Most of the level-1 techs have no clue what I'm even talking about when I call in. I'm considering  switching to CenturyLink in April unless Cox can provide answers and a resolution soon. Suggestions??