Ken is right about fuel filters. After I found a cat hair inside the spray bar on an engine that had been running for years I put fuel filters on all my planes. Yes my cat is a shop cat and wanders all over the shop when I am in it. Reclines on top of the tool box in the path of the overhead heater. I even use a fuel filter in on my fill line on the fuel bottle. When defuelling I have a short piece of tubing and another filter that filters from the tank to bottle then it comes off when I fuel the next time. This stops any contaminates getting from the tank to the front end of the bottle fill filter which would end up putting it right back inside the next tank. Clean fuel is a must for those small openings in the spray bars and such.
Dennis