po300 OBD code came up on a scan tool which indicates a random misfire.

A professional scanner can run misfire data that will monitor all cylinders on screen and show misfire history. Suggest you find a mechanic that has one!

Just to mention; GM has a bulletin out to address a random misfire issue on most models for an Intake Air Induction Service to clean the carbon, and build up on pistons, injectors, and valves. Just something to consider.