I have a nice handy little 35cc McCulloch chainsaw, bought new last fall. I've probably put about 20-30 hours on it total so far. It calls for a 40:1 fuel/oil mix, which I did at first by mixing a big batch and just refilling from that. Now, I do it in much smaller batches, so I'm probably over-oiling it. The last two times I've used it, I run into a wierd issue after about an hour or two of running. It will lose power badly with more throttle, and the chain will actually stop during cuts. I go WOT, and the saw sputter's and die's or just revs extremely low until I pull it off the load, at which point it sputters and I have to feather it to keep it from stalling. If I set the choke half way during this condition, it revs up with throttle, but still loses power as soon as the chain hits something, and barely cuts. This first happened last thursday night when I was cutting down a big tree in my yard, so I got all irritated and put it away. I took it out sunday thinking it wouldn't work well at all, and it fired up almost instantly, then cut through the same tree like butter. I was happy again, so continued cutting up the tree, and after about an hour or so, the same lost power thing happened. I had filled up on fuel 2x, too. The first time it happened, it was a warm day, but not hot. The second time, it was a pretty hot day. So I was thinking maybe it was overheated?? I don't understand how it overheated like that, though. It had plenty of chances to overheat before as I was using it. Also, the fuel I used the last two times was premium/high octane (93 I think? I got it when the motorcycle wouldn't start). I would think it would run better with that, but I don't know. My Dodge seems to run better on lower octane... So any ideas? So should I focus on a cooling issue, defective/damaged engine, or a fuel issue?