Do what The Head is saying, check the O2 sensor.
Did that octane booster do anything on your butt dyno? I tried some toluene before and it seemed to make a little difference, aside from making the exhaust note a little different.
EDIT: You could go get a bottle of Marvel Mystery Oil and try to see if that will clean it out. I dunno if that would help any. I just want you to be the guinea pig.
If you do, then check to see the condition first and then pull it after a tank of gas and see if it has gotten any better.