2018 l3901. 469hrs. Always inside. Today goin down the road 2500rpm ish. I hear a small knock that becomes quite noticeable. I slow up head back to yard. No codes. Shut off a few times and start still there. After bit of putting around noise fades to only higher rpm’s 2000 plus. Now it seems to be back to normal. Im figuring an injector gremlin ? Any thoughts. Thx for any insight.