RE: engine idle + vertical = engine quits?
Well... I would consider the engine dieing in the manner described.... normal.
Engine at dle... minimum muffler pressure to the fuel tank. Nose straight up... maximum gravity to overcome getting fuel to the engine.
The bubbles he's seeing would be air entering the fuel line via the fuel jet in the carb. Nose straight up at idle is not a good test for seeing if the engine is set correctly.