[w.michael]

I've read your post #11 carefully. I am not seeing what you are seeing in the sight tube, so I may have this wrong. But please consider:

I think the float valve could be sticking in the closed position. When you let the car idle, the float comes all the way up, closes the valve, and in sticks in the closed position. Then when you burn all of the gas out of the bowl, the engine stumbles and stalls. Possibly what you are seeing in the sight tube is the fuel level splashing and bubbles resulting from the splashing just as the fuel level gets very low, just before the bowl runs dry.

Try letting the engine idle again, and as it starts to stumble, tap on the carb bowl in the area of the float valve and see if the engine recovers. Try it again, and as the engine stumbles, pull the choke a couple of times and see if the problem clears. Either of these could indicate a stuck float valve, and not boiling fuel.

Some of the new float valves just simply stick.

I may be completely wrong about your car, but this sounds similar to the symptoms my A suffered due to a sticking float valve.

W. Michael