blindside, if you run 91 and have problems, you have a problem with your engine. Not trying to call you out, but there is a reason toyota spec'd these engines with 91+, they are high(ish) compression running aggressive camshafts (more so than the car version, not as strict emissions on water apparently). They need the slower burn of higher octane to make optimal power. When you say 87 gives you better performance, have you pulled the battery for a few minutes after testing this theory? The ECU needs to reset the LTFTs and adjust the spark maps for the difference in fuel.
FWIW, only 91/92 goes in my boat. Seattle has 92 sometimes but usually its 91. Only Shell/Chevron gas for all my land rides and the Epic gets a full tank at the beginning of the year of it. During the season whatever the gas docks have unfortunately.
It's probably because no one around here buys high octane, it gets old and then is actually a lower quality fuel than the fresh 87 octane.
