[Rob Doe]

2935ford, here are some of my early morning thoughts:

Your initial comment: "The minute it gets up to temp.......backfires, jerks, hops then quits running." leads me to suspect a slow starvation of fuel.

To test this, when the popping and jerking starts, turn the engine and fuel valve off, remove the fuel line at the carb and loosen the line at the filter, then rotate the line up so that you can blow back through the line to clear any sediment that has migrated into the top of the fuel valve at the bottom of the tank. Use and air gun or add a piece of clean hose to the line and use your lung power. If its a quiet area, you should hear the bubbling in the tank. I'd do this outdoors with a fire extinguisher handy.

Do you have a pencil filter in the top of the valve?

My speculation: Backfires come in two flavors??? A backfire in the exhaust system is sometimes referred to as afterfire and backfire through the carb air horn is a backfire. Intermittent electrical problems can create both types, but backfires via the carb alone are usually a lean condition.

Test the fuel flow by opening the valve and running fuel into a jar or bottle. It should shoot out a full stream a couple inches and fill several ounces in a few seconds if not restricted.