that gas is junk. probably full of condensation.
a few years back, i was in the briggs and stratton factory school and we did a failure/analysis course on fuels.
87 octane gas has a shelf life of about 30 days from the day it was refined. it may have sat on the delivery truck for two weeks before it reached the gas station. one of the biggest problems with not only the 87 octane, but all grades, is the additives used.
one of the biggest additives is alcohol. lower grades of gas have more alcohol added then higher grades do. alcohol attracts water, breaks down the fuel content, and evaporates quickly. it burns much hotter than the actual gas fumes do (keep in mind that gas is not flammable, it's the fumes/vapors that burn) and it burns in a really dirty way. and if your gas has ethanol, it's even worse. case in point;
my wifes van started acting up in the beginning of november. it would not start when cold unless i pumped the gas pedal while starting. unusual for a 2002 fuel injected vehicle. seemed like a choke problem. so i replaced all the throttle body sensors. not cheap to do. that did not fix it. within a weeks time, it got worse. finally it would not start at all. i pulled all the plugs and they were seriously fouled. so i replaced them thinking that maybe the air filter was bad (only maybe 1000 miles on it since i changed it) or they fouled from trying to start it over the last week. new plugs did not help either. i finally got it to start and run and told her to take it to my friends shop so he could plug it into the computer and tell me what was wrong.
the van didn't even make the 20 min drive, it broke down on the freeway. it only has 26,000 miles on it, so i was really stumped. turns out that once the diagnostics was run, the ethanol ratings on the computer were at 78%. they should never go higher than 20%. she got a bad batch of fuel. i had to then have every sensor on the engine block, except for temperature sensors for the cooling system, and the two oxygen sensors, AND the catalytic converter replaced because the ethanol burned them up. cost me another $439.00 on top of the other parts i replaced trying to figure out what was wrong.