Have you checked to see if you have good fuel flow through the fuel pump?
Sisnce you changed carbs,,, did you use a new carb or a used one?
If it was a new or rebuilt carb, I would check out the fuel tank the fuel lines and the fuel pump.
Now it is possible that you have a poor connection to the ignition feed from the battery. Look the connections over real well and with the truck running at idle, wiggle the wires and connections to see if you get anything to cause the engine to stall or die.
Be careful you don`t get zapped by the spark-plug wires eek
One more thing, check the wiring and connections close to the heat of the exhaust first so you do not get burned

There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!