P0301 Chevrolet - Will using hi-octain gas fix problem?

Question

replaced: coil, wire to plug, and re-gaped plug.

Answer 1

P0301 Misfire number 1 cylinder

No. if the fuel was the issue you would set a P0300 which is a random misfire code condition.with more than 1 cylinder, The fuel injector would still need to be checked, Rule out a mechancial condition that could have set the code by the use of a either a compression test of a leak down test.