bang things, thats how i found my problem.
was all very similar, then i realised slamming the door set it off, would stall. i kept banging things till i found it to be the ecu. one tap on it would make the car cut out momentarily, just like yours. in my excitement that i had found the problem i banged it a few times too many till it didnt want to come back on lol.
problems sorted now, so i suggest you bang your ecu with your hand and see what happens lol. minor bumps in the road could be setting it off just like mine.