Tractor acts starved for gas

I'm not familiar with the specifics of your ignition system but to quickly check the spark after the engine dies, remove the center wire from the distributor cap, turn on the key and try a start while holding the wire near a good ground. (It make take two people to do this.) You should see a FAT,BLUISH-WHITE SPARK FROM THE WIRE. If you do, your ignition is not the problem. If you don't then check out the primary ignition cicuit.
Does your carb have a drain plug on the fuel bowl? If it does, open the tank valve and hold a container under the carb and remove the plug The gas should STEADILY gush out LIKE A COW PEEIN' ON A FLAT ROCK for as long as the plug is open and there is fuel in the tank. Do that for 45-60 seconds. If the flow just dribbles or is intermittent then there is a resriction in the fuel delivery. You blew out the gas line but does your sediment bowl have a filter or screen in it? (What did you find when you cleaned out the sediment bowl?)What about the fuel elbow in the carb? A lot of them have a screen in them. You could have a restricted float valve or a flow bowl full of crap and corruption that's not letting the float drop. You float might be damged or the pin could be badly worn. Make sure the vent on the fuel tank is open.

Hope this helps you.

Check your coil. I'd swap it out for a known good one.

Allan

Points and condensor,assuming the M has those.

Might try running it at night, when it dies, see if you are getting a bright steady spark.

Bad switch is a possibility, but it dosen't sound like it.

If you eliminate ignition problems, you will have to start on the carburator. I don't know enough to advise on that, but I would run it untill it has problems, then disconnect the fuel line at carburator to see if you have a strong flow, being careful around a hot engine. Good luck.

KEH