2008 Ford Ranger 3.0L V6 P0304 Cylinder 4 Misfire: Causes, Fixes & Solutions

I've been experiencing a persistent cylinder 4 misfire on my 2008 Ford Ranger with the P0304 diagnostic code for several months. I've already replaced all spark plugs and addressed a coolant leak from the timing cover gasket located directly adjacent to cylinder 4—this repair has resolved the antifreeze leak, but the misfire issue remains. The engine runs roughly at idle, especially if not warmed up properly. When starting cold, it feels extremely rough during acceleration, but smooths out after driving for a few minutes and allowing the engine to warm up. I've been advised by multiple sources to replace the spark plug wires or coil pack, and some suggest faulty fuel injectors as a possible cause. I've already run a bottle of injector cleaner through the system with no improvement. Given that the P0304 code points specifically to cylinder 4, what are the most likely root causes? Are there any diagnostic steps or common fixes for this issue on the 2008 Ford Ranger 3.0L V6 engine?