Chewy buildz

Hi, would appreciate any thoughts you may have. I’ve just swapped a known good VQ35DE into my 2003 UK manual 350Z, using the donor engine and harness but keeping the original ECU. It starts and revs fine, but has a bad misfire at idle. Only code is P0300. I’ve narrowed it down to cylinder 6 because unplugging that coil makes no difference at all. So far I’ve: Swapped the coil with cylinder 2 Swapped the spark plug Swapped the injector Confirmed the injector is clicking Confirmed injector pulse with a noid light Compression tested cylinder 6 at 185 psi Smoke tested the intake with no leaks found Confirmed 12.5V at the coil connector Checked continuity from the coil wiring back to the ECU Checked the engine grounds and added a direct ground from battery negative to the engine Unplugged the MAF, which made it run worse The fault has stayed on cylinder 6 through all of this. Bank 2 short term fuel trim was around +25%. The donor engine ran perfectly before it came out. I did remove and refit the crank sensor during the swap. I’ve got an oscilloscope arriving tomorrow, so my next step is comparing the ignition trigger on cylinder 6 with a working cylinder. Has anyone come across something similar after a VQ35DE swap?