shmkr,
Reading the list of all the things you have done and changed, It's hard to believe that it's the fuel system. How are you determining there is no fuel in the carburetor?
What happens if you let the engine fizzle out, then pull the fuel line at the carburetor and crank the engine over, sticking a can or bottle over the end of the fuel line. Does fuel come out or is it really bone dry!
Does this problem happen if you let the rig sit in the driveway and idle..will it still die after half an hour or so! That's way too long for a typical fuel blockage to happen, and especially if it does it consistently, from a cold engine to a warm engine.
The empty carb is the giveaway, but if this isn't actually happening, the ignition could be suspect. Coils have been know to give up the ghost when they warm up, then magically work again when cool.
A little more troubleshooting can really narrow the field of possibilities on the gremlin.
Stuart