pac man alcohol tolerance?

so im brewing some hard apple cider using pac man yeast. i put a bunch of honey and extra apple juice concentrate in to up the sg. it came out at .o71 at 75 degrees. ive read rogue brews at around 60 degrees so ive kept the fermenter at about that temp. it bubbled very slow the whole time and now, 3 weeks later, it stopped. i took a test sip and it still seemed pretty sweet, about plain apple juice sweet. i cant think if why it might not have done a full ferment except that maybe the alcohol content is too high for the yeast. i know rogue brews some barley wines.. do they use pac man for those to? at what point does this yeast start to get inhibited by the alcohol they produce? the other possibility is my yeast strain isnt as strong as it should be. its left over from an old batch. ive had it in my fridge for about 2 months maybe. i pitched it strait into the beer without using a starter culture or any kind of yeast nutrient... but it seemed to be fermenting fine, just really slow.

I would guess its a yeast health issue. You answered your own question by saying its been sitting for two months and you didn't make a starter OR add yeast nutrient. I would make up a starter with some fresh stuff and some yeast nutrient, then re-pitch. Your temps are good, just probably didn't have enough healthy yeast to do the job and they're overwhelmed with the gravity.

You can try adding some yeast nutrient, then maybe re-pitch a starter if that doesn't work.