In OP's place, I would go as far as upgrading the OS to latest insider build, they usually are more advanced and sometimes even more stable, also every single driver and major application on the pc must be upgraded to latest version, such as anti virus, any resident tray apps, etc.
Also, I would try to unclutter the system as much as possible, using autoruns to disable any services and startup items that are not absolutely necessary.
As mentioned, one of the easiest diagnostics is to install LTSB version of windows in dual boot on another partition, and check that for problems, rather than mess with the crippled system.