Hi, I’ve had the same problem with mine. The crew at the Apple Store,, after several tests said that it could be the motherboard. I searched the internet and found the solution in this Random Shutdown on MacBook Pro I did this in June 2018, and my MacBook Pro works flawlessly since. FYI - The problem is faulty power chips on logic board! (FDMF6808 to be precise. Should be replaced with newer FDMF6708). We turned off one driver, that is for Ethernet via thunderbolt. Somehow it helps with our problem. It is possible, you don’t need that functionality, like me.