What we suggest is that you perform a clean boot. A clean boot is performed to start Windows by using a minimal set of drivers and startup programs. Check this link for more information.
Also, we'd like to ask you to take note of every application that you use whenever the Surface overheats and monitor those applications after performing a clean boot.
It is normal when you are charging a device or if the device has high CPU for it to become warm to the touch. Surface devices will when they reach maximum allowed safe temperature automatically shut down and display the thermometer icon. For additional information see our Safety and regulatory information and Windows doesn’t start on Surfacepages.
Regards.