2002 Ford Taurus 3.0L Engine P0302 Code: Intermittent Misfire in Cylinder 2 - Diagnosis and Solutions

The issue began Wednesday morning. The vehicle ran smoothly the previous night but started running poorly upon startup on Wednesday morning, with the check engine light illuminating. After circling the block and returning home, I used my OBDII scanner to retrieve P0302 (Cylinder 2 Misfire Detected) and P0316 (Poor Cold Start Failure) codes. I replaced the spark plugs as they were due for replacement, but the problem persisted. I then obtained a new coil from a junkyard and installed it—immediately, the engine ran smoothly. However, upon re-installing the original coil, the misfire returned. When I put the junkyard coil back in, the issue remained present. This vehicle uses only one 6-terminal coil (not individual coils per cylinder), which makes diagnosing more complex. After replacing the spark plug wires with new ones, the problem still occurred. I planned to swap injectors to see if the misfire followed the injector, but before doing so, I attempted to start it multiple times. On the sixth attempt after shutting off and restarting, the engine ran smoothly for a short drive. However, during a stop at a restaurant, it started again and ran fine for about 1/4 mile before the misfire returned. Given that this is an intermittent issue, I believe it's not mechanical—such as a bad valve, which would typically not resolve itself and then reappear. While some forums suggest an oxygen sensor fault, I don't see how that could cause only cylinder #2 to misfire without triggering an O2 sensor code. I am now focusing on the possibility of a faulty injector in cylinder 2. I plan to perform an injector swap if no other solutions emerge. I appreciate any additional insights or suggestions from experienced users regarding this specific issue.