Do the one minute calibration first and foremost with the fuel that you are going to use and then try it. Do you have a muffler modd on it or not?
That bogging at the beginning of a cut sometimes and sometimes not. It seems that it is adjusting from light work to heavy cutting. I get it sometimes and sometimes not, when dropping a 441 into a big tree top after limbing the log up to that point.
Another time you can get this happening is when you have just started the saw and then go right to heavy cutting, it will bog for about 1" of a big log and then just rip up to speed.
I think the computer is figuring out the right mix, so ................. its going from idle or light limbing work and then you drop it into a heavy log and it is making adjustments.
Its different for sure, but one thing that makes me "feel good" about it, is it is always running rich, so you won't burn up a piston/cylinder from being lean, I've yet to ever catch the computer making the saw lean, mine always are running rich, which gives great torque for working ......... not so good for cookie cutting races.
I'm running 50:1 Amsoil Saber, but sometimes if there isn't enough in the bottle to finish out a 5 gallon jug, it might be 65:1 or 80:1 and I don't have any problems with longevity or tuning. I'm not against heavier ratio's, just haven't personally seen where 50-80:1 on Amsoil Saber was a problem.
But I don't think its fuel, because, I get that slight hesitation on whatever gas I'm using. I think the calibration will be your best bet for now, let us know if that fixes it, as I'm interested in if that fixes it for you. I'm not getting it too bad or much at all with the saws once they are calibrated.
Later,
Sam