2010 fuel problem (gas)

Otherwise, there must be a piece of crud blocking the fuel flow intermittantly at the tank fitting, the sediment bowl, or one of the elbows.

(Are you SURE the carb runs out of gas, and you're not loosing spark?)

(Be safe while doing this)... Remove the carburetor bowl drain plug, and see how well the gas flows into a catch bucket... there should be a quick flow of about 1/2 cup or so of gas, as the bowl drains, then a steady flow, as the gas flows into the carb through the inlet valve needle and seat. It's hard to quantify that flow, but it must be enough to sustain the engine at full speed/load.

WOW! I'm impressed. I didn't know it was possible to post drawings like that.
1. Mine is not set up that way, someone probably changed it long before I got it. In fact it doesn't even have a sediment bowl on it. The fuel line connects to the cut off valve which is integral with the strainer. Then runs to an aftermarket filter located 2 inches from where the line goes into the carb.
2. I have not seen a tank vent like the one in the drawing. I have tried running it with the cap off and it does not seem to make a difference.
3. I'm certain it's a fuel problem. I have checked the flow with the engine off. To do this I disconnected the line from the carb and there seems to be plenty of flow. It is as if the engine is using more than is available. In fact when the engine starts to show signs of cutting out I can watch the fuel level in the filter diminish until there is none visible just as the engine dies.
4. I did flush the tank when I removed the strainer/cut off valve.

(The diagram is linked from JDPARTS, and I didn't notice a serial # break with the vent system. I have a 2010 in the shop right now, but it's a diesel, so looking at it's fuel system won't prove anything.)

Can you go to a sediment bowl sytem like it originally had?

The tank shutoff valve, # AT36766, is still available, too, as well as at least some of the lines and fittings.