2013 mustang po355

Okay so I have a 2013 mustang v6, about 200k miles and its a manual. It has code po355 and I started with changing the spark plug and coil but the issue stayed. I checked the connector and noticed it wasn't getting grounded like the others. I followed the wire back to where it plugs into the PCM and it has continuity to the PCM connector. I think I'm stuck but if anyone knows anything I should check or do before sending it to the stealership or a real mechanic