94 octane stall

i found a dramatic difference going to 94...pulled harder and smoother with no detonation.I did get one bad tank years ago ...like you the car would barely get up a hill without detonation.I buy from a very busy Petro Can station now and haven't had any problems yet.I never put more than half a tank in so the gas is gone in a week or two.Problems may occur if it sits in your tank for 2 or 3 months.All gas i believe in Jan 2017 was mandated to use 5% ethanol.Petro Can 94 has 10% so it's not much.
Run a post on Ethanol and you might start a war!