MacBook Pro “15 (A1398, Mid 2015) crashes sometimes, and boots inconsistently, but works perfectly in safe mode

I am having a problem with my MacBook Pro “15 (A1398, Mid 2015) - during operation in normal mode, it sometimes and highly unpredictably freezes, and shuts down. When switched on, it boots but half of the time it does not boot correctly and you need to boot 2-3 times to make it to normal mode. It also shuts down when I send it to sleep. Also, I use it in clamshell mode, so have an external display. It behaves not very different out of clamshell mode too. An important point is that it works perfectly in safe mode (boots properly, doesn’t crash, and sleeps and wakes properly). So I think we can eliminate hardware issues.