FWIW
I had a year old can of Powermaster 15% stored under similar conditions and have had the exact same problem as you have described with a OS .46 engine always ran great, till I opened this can. Same symptoms on the ground ran great, full throttle no problem, throttle back in the air it died, anywhere from slow cruise mid or 3/4 throttle. Used another brand of fuel problem went away, Hmmm. Another guy at the field had a can of the same fuel this year similar problems, new fuel, problem when away...
Can't say what your issue is the same but...
Now I never tried the fuel in anything else so I can't say for sure it was the issue. But...