I bought this generator 3 or 4 years ago. I "accidentally" sprayed a small amount of carb cleaner into the air intake several months ago while it was running (the carb cleaner says "will attack plastic" right on it). It ran fine for several minutes and I shut it off. I hadn't run it again until yesterday (starts easy, single pull). From cold start, the exhaust is black and it takes 10 or 20 seconds longer than normal to run at full capacity. After that it runs fine and the exhaust is clear until I shut it off, but if i leave it off long enough to cool down, it does the same thing again. I don't see any damage on the plastic air filter case, but there is a very small pool of oil at the bottom of the filter and the filter has some extra oil in it. I am thinking it is the oil causing too much resistance to air getting through, so I soaked the filter in dish detergent and dried it thoroughly. I haven't tried again to see if it continues, but is it possible that I ruined some seals that is causing this?