P0204 Fault in 2005 Dodge Grand Caravan: Injector and Harness Issues

I recently encountered a P0204 diagnostic code on my 2005 Dodge Grand Caravan after the check engine light activated. I immediately replaced the fuel injector, but the vehicle still ran roughly and the P0204 code persisted. Upon further inspection, I discovered that the fuel injector harness was sitting directly on the exhaust manifold, causing some wires to melt. I replaced it with a used harness and tested the circuit—initially appearing functional. However, after installing the new harness, the P0204 code reappeared. I then installed another fuel injector, but the same code continues to show up. Given that I do not want to replace the PCM (Powertrain Control Module), what troubleshooting steps should I take next? Are there any other components or wiring issues that could be causing this persistent fault?