1999 Buick Lesabre P0300 Random Misfire: Diagnosing Without Replacing Control Module

I'm experiencing a random misfire on my 1999 Buick Lesabre, which has triggered a P0300 diagnostic code. I took the car to AutoZone, where they initially suggested replacing the oxygen sensors. After swapping out both O2 sensors, the issue persists. Using my CarMD device, I confirmed the presence of a P0300 code. I replaced all spark plugs and ignition wires as they were showing signs of wear, but now I'm not getting any spark from the top coil pack. When I swapped the coils between banks, the spark returned on the other side, indicating that the individual coil is functional. However, testing revealed that the control module for the top bank is faulty. I understand that attempting to replace the coil control module could result in further damage—especially at a cost of $150. I'm concerned about whether there's another root cause behind this random misfire before replacing the control module. How can I confidently identify and resolve the underlying issue without risking additional expenses or component failure? Any advice would be greatly appreciated.