Could be any of the above, another culprit is too much time idling, engine temp too low, it takes about 200* to cook off the alcohol from the oil, the alky turns to a vapor, then condenses back to a liquid in your catch can, along with some oil, I usually set my fuel flow at 3/4 gal per minute, this is more than plenty, and also doesn't dump the floats, and the floats can be a problem, if you can find a set of brass floats, they don't soak up fuel like the foam floats do, a good ck is to take them all out, and put them in a small container of alky, and see how well they do, a lot of guys either remove them, or the bowls, and let them dry between times at the track, a lot of trouble, but these are old parts, and weren't coated for use with alky. Ck the bowl level by filling them with the pump, then remove them, and ck the level, should be 3/16 from the top without the float, all this stuff should keep it to a minimum. Could be your choice of oil too, not all lubricants work well with alcohol! Good luck! Bob