1 idle speed to high - not likely
2 ignition timing incorrect - check it, can cause hot spots
3 incorrect spark plug heat range - same as 2
4carbon build up in combustion chamber - see treatment below
5 valves sticking - not likely
6 bcdd or ficd system not operating correctly - Huh?
7 valve clearance incorrect = not likely
8 intake air leak - or other lean out like too small jets, or:
9 egr system not operating correctly - is yours leaking?
10 fuel shut off system not operating correctly - you don't have one, do you? No wires to the carb except maybe a choke heater???

I see the vac hose is off the egr, but are there deposits in there that at holding the valve pintle open? I'd consider making a block off plate for the egr valve location, too, or tap and plug the ports, which are close to 3/8" npt pipe plug size...

Try fogging water spray into the carb with the engine at a high idle, like 1500-2000rpms. This should blow out any carbon deposits in the combustion chamber and on top of the piston, and those are what commonly get white hot and provide a source of ignition to cause the dieseling, like a glow plug. I've been able to kill a dieseling engine by stepping on the gas, sometimes in rapid succession, and thus flooding it out. Kinda like putting out a fire by dumping gas on it, right? Still works.