91 q45 problem

i put midgrade gas in my q45 now it is knocking but the car runs perfect sometimes the knocking stops but when i press the gas it starts back up knocking there is nothing wrong but that knocking noise how would i know if it is the fuel injectors and how do they cost and what kind should i get thank you

i put midgrade gas in my q45 now it is knocking but the car runs perfect sometimes the knocking stops but when i press the gas it starts back up knocking there is nothing wrong but that knocking noise how would i know if it is the fuel injectors and how do they cost and what kind should i get thank you
Must run at least 91 Octane if engine is perfect (clean and in OEM specification).

You are hurting your car! Stop it!

Your knock sensors are probably dead anyway. Check them via the ohm test.