Totally agree, My 2017 Pilot did exactly what you described with only 15000 miles and it was only a years old @ the time, it will bang hard like I got rear ended and once shut off, it will be back to normal, dealer not able to dulicate issue until finally one day it happend on camping trip and CEl/Trans light all came on, we pulled over @ gas station, shut off the car and waited for about 1/2 hour, restart and car drove fine, back to dealer and it had P0848 transmission pressure switch gone bad and was a easy job and was told this is pretty common on this transmission. BUT without the code, Dealer did not know what to do for 3 visiits.Sounds like failing transmission pressure switch to me. They can be intermittent like that.
Hop this info helps you. Good luck.