octane

[gundersonr]

i have a 150 HP Commercial Johnson engine
Model J150WPLSSC; serial Q04805840

The nameplate states octane but i'm not sure what it means. It looks like
)87 (r+m)/2.

does this mean 87 octane is ok or should it be greater than 87?

Although this motor was manufactured in 1999, it didn't come out of the crate until 2010.

engine starts fine but usually kills when throttle is increased unless it is choked. Runs fine at high speeds. Any idea?

[boats.net]

87 octane should be ok, sounds like you will need to have the carburetors removed, thoroughly cleaned, linked, synced and adjusted.