My car was running fine and then it started missing and the check engine light came on and off

Sounds like diagnostic testing is required. Diagnostic trouble codes will be set that can be retrieved to help guide where to look first. You could have an ignition spark issue, a base engine misfire issue, a fuel delivery issue. Do not continue to drive the vehicle in this condition, as you can damage catalytic converters and other components by continuing to drive with a check engine light flashing. https://repairpal.com/repair-shops/subaru-repair-and-service-in-du-bois-pennsylvania