Yes, you need to fix the problem. My suggestion is not to clear the codes after you fix the problem so you don't have to run all of the readiness tests meet the emissions requirements.Passing the inspection is indeed important. But ignoring the problem will cost you greatly if you continue to ignore it. Misfires can lead to burned valves and damaged catalytic converters. Next you'll be telling us about the P0420 codes you've logged!
If you can't solve this yourself, seek out a trusted mechanic.
As a professional mechanic with a 100% success rate on resolving P0300 codes, I appears to me that you have outstanding advice on how to fix the problem in the thread above.