Something like this would happen in my Civic too, not a decline but a small bump on the road like where two concrete blocks meet would set it off. It turned out to be a MAP sensor issue. This is something in the exhaust that feeds back to the controller, it was giving wrong values which caused the software to decide, fuck it let's shut it down. We all know the Toyota acceleration story. So the point of my story is, dont trust even reliable cars' software.