Have you pulled the fuel hose off the carb and checked fuel flow from the tank ? There is another filter in the fuel tap. The other thing mine suffered with once was a high resistance spark plug cap (just one) would run fine when cooled down but then pop and backfire warm and stall (on the side of the road north of Gisborne) the manual says check them together which showed up no fault but when you removed them and checked individually one was very high resistance, new cap and it ran sweet.
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