I have installed a thermostat in the coolant line feeding the vaporizer & it has helped a great deal in the life of the regulator, but the injectors still get hot & the wax in the fuel turns to hard tar & clogs them. I'm unfamiliar with what's inside the fuel side of the injectors, so I'm hesitant to just use brake or carb cleaner- I don't want to ruin the injector if there's a chance it can be cleaned.

As far as the plugs- I am aware that a hotter heat range was the norm on older lifts, unfamiliar if that's still the case. I'm not sure though how the heat range of the plug would affect the tar build-up in the injector.