Originally Posted by 1995Civic
Putting Premium gas in your civic will do absolutely nothing except break your wallet. There is no need for it whatsoever. Civics actually run better on what they are made to use, which is regular unleaded. It's built for the intentions of fuel economy, and people always seem to have this sense that premium gas will make it run better. It actually makes it run too rich if anything.
My car is N/A with many upgrades, it runs best on unleaded plus... which is 89 octane gives me the best Power and fuel economy.. If I use 87 octane, it gives me poor performance good econ, and with premium 91octane, good performance poor fuel econ. Hopefully my VAFC2 will give me even better power n fuel econ.
As for the idling issue, seems like a vacuum or Intake Manifold leak.