2001 Toyota Tacoma P0303 Code: Third Cylinder Misfire Diagnosis and Troubleshooting

I own a 2001 Toyota Tacoma 2WD with a 2.4L engine. The check engine light has come on, triggering a P0303 diagnostic code, which indicates a misfire in the third cylinder. This vehicle uses a distributorless ignition system with four individual coil packs, all showing identical resistance readings of 13.5 ohms. I have already replaced the spark plugs, and while the engine ran smoothly for one day, it became shaky again, with the check engine light reactivating. To test potential injector issues, I swapped the third cylinder's fuel injector with the first cylinder's injector. After performing a reset using my OBD2 scanner, the code changed to P0302 — indicating a misfire in the second cylinder. This unexpected shift puzzles me: could there be an error in wiring or installation? The vehicle has accumulated 96,000 miles and I'm seeking clarity on what might be causing this intermittent misfire behavior.