Generator hard to start and sputters like its missing

When was the last time you ran it Prior to this problem? When you rebuilt the Carb, did you pull out the plastic plug on the top of the carb? Many B&S carbs has a air plug up top that clogs. When gummed up, it causes surging. Did you clean all the tiny holes in the Jet and Emulsifier?

If this unit dies under load conditions, decrease your load and try it again.
If this happens under no-load conditions, check your fuel supply. Start with the filters, then check pressure and flow.

could be a ton of things. water in the gas will separate in the carb and effect it. restrictions in the fuel line/filter is another. I would look there first as it does not appear to be electrical or mechanical.

THAT SOUNDS like a VERY LEAN condition. The exhause glowing is because its so lean. The stalling the sputtering. OPEN the gas valve more WHILE its running. With a load if possible.. If you have a tri fuel kit like I do, going from propane to nat gas I need to open the load block (gas valve) 2 turns more .Then it starts and runs great.

running out of time and too rich
suggest that you call in an auto gas technician to check and adjust the regulator /converter for the gas to get it running right

Sounds like the carb is dirty. Try running the generator for a bit and when it sputters try slowly closing the choke to see if the generator will come out of its sputtering. If it does come out of it then you can start at the fuel tank and remove the filter screen in the tank and clean it well with an old toothbrush. If it is plugged with varnish it needs replaced. You can get by testing the unit by leaving it out and reassembling but you will need to replace it before actually using the generator. If the filter is clean check fuel lines for plugging and varnish along with the inline filter if it has one. If the lines and tank are clear you will need to pull the carb off, remove the bowl and clean the carb and jets. You may need to use a commercial carb cleaner if varnish is bad but be sure any plastic or rubber parts are removed before cleaning. Only immerse the entire carb if it is necessary. Try to remove the jets for cleaning. They can be a pain at times to remove but the jets and bowl are safe to immerse in carb cleaner. If the rubber o ring sticks to the bowl remove it before putting it in cleaner.

The reason choking the generator works when jets or fuel lines are plugged is because the choke blocks most outside are from entering the carb causing the engine to "****" harder through the jets in the carb.

Sounds like possibly a split fuel line or fuel component in the fuel tank

you dont say if diesel / petrol.
if petrol check the choke mechanisim.
if diesel injector may need cleaning or re setting

try to adjust fuel mixture screw

have mass airflow sensor cked.