I pulled and checked all 3 carbs about 3 or 4 weeks ago and all 3 was clean as a whistle. I have looked at all the fuel lines when I replaced the fuel filter and rebuilt the fuel pump and they all looked good, no cracks nowhere and they too were clean and smooth on the inside and out. Can a fuel line be breaking down with no visible evidence?? I'm asking because I really don't know. These boat motors are like reading Japanese to me. I'm just trying to learn as I go where I can gather knowledge for later uses. I pulled the lower unit yesterday before I found the spark problem and it all looked good. I just can't understand how I get a bogging problem, it goes away for a few days after I change the fuel filter, fuel pump and blow the carbs out and run sea foam thru the gas with non ethanol gas and then come back but not as bad. When I say not as bad, when it first happened, I could only get 1800rpm at WOT, when it started again, now I can get 3200rpm at WOT. It will come up on plane eventually but I don't have the top end speed.