Please, please, please tell me if you are taking in fuel from the gas can or the gas tank, with all these tests? I assume you are taking from can. I assume you know NOT to use the gas tank until it is replaced or thoroughly cleaned. I do not like the 30 second timing for fuel flow. If you are taking fuel from a gas can and taking 30 seconds, you need a new pump!!!! Also, you will need to rebuild the carburetor. These are the two baseline items to get done before you fiddle any more. I think you have at least two problems at once. Pump and Carb. Try NEW pump first and see what difference it makes. Get a new pump. The manual pull choke that you keep talking about is so simple of an item with very simple usage, it is not worth discussing yet. You are needing it WAY too much. You will hardly use it when all else gets fixed. All it does is enrich the fuel mixture by blocking air/changing vacuum for a short period during cold starts/cold whether. Fuel does not evaporate/vaporize/atomize well in cold air. Once the motor gets hot, in a few minutes, the choke is opened all the way. If you are in a hurry and need to get movin', you can open it gradually on the road.

Don't get anything but a stock pump. No performance pumps! Replace the inline filter, replace the carb cartridge filter inside inlet (large nut).
Proper pump part numbers:
O'Reilly's M16058
Autozone 40254
Or equivalents, you are 4.6 L motor.
3.5 PSI, two port pump.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn