Nipper,
I will not profess to be an expert in the chemical interaction between gasoline, alcohol, and GRP, but I know something about Mogas use. I have more than 3000 hours of trouble free flying on it.
Perhaps you have a compatability problem in the aircraft fuel system, and you are getting decomposed particles. To assure that your engine runs smoothly it such a case, a good fuel filter just before the carb will be your best defense. Yes, if disolved solids are reconstituting themselves in your carb, after the filter, that could be a problem, but frequent use will prevent this. Consider the possibility that the affect of the Mogas on the non-metallic components of the fuel system, might not be unique to Mogas, Avgas might have those effects too. If it is an older aircraft, it might struggle with either fuel.
Alcohol has potential for adverse affects too, but I will leave that for others to comment upon.
Presupposing that you are running a low compression engine, it, and the environment will be happy that you are using Mogas instaed of Avgas. A better understaning of the fuel delivery system is what you need. Having the gunk in an undesired place is one thing, why is the gunk not upstream where it is suppose to be is another. The long term airworthiness of your fuel system requires you understand what is happening. Some informal home made long term compatability tests with the materials, and your local gasoline supply could be informative. A good fuel filter, regular inspection and cleaning should keep you flying safely in the mean time.
I am a Mogas proponent, but do be sure that your use of it is approved from an STC point of view, if it is a type certificated aircraft. Some aircraft were not STC'd because they had fuel system problems. That's why the engine and airframe STC's for Mogas use were often sold separately.
Pilot DAR
Pilot DAR