2003 Mazda 6 U0101 Diagnostic Code: Stalling and Dashboard Display Issues

I recently had my 2003 Mazda 6 undergo a complete engine motor replacement, after which it ran smoothly for some time. However, I'm now experiencing intermittent stalling issues. The car runs fine in neutral and will not stop when the throttle is released — but shortly after releasing the gas pedal, it suddenly stalls. It restarts immediately, though the problem recurs frequently. Additionally, the dashboard display (specifically the radio station indicator) shows erratic or incorrect readings. I've retrieved several diagnostic trouble codes from the OBD2 system: P0113 - Engine Coolant Temperature Sensor Circuit Malfunction U0101 - Communication Failure Between ECM and Instrument Cluster U0100 - Communication Failure Between ECM and Body Control Module The primary issue appears to be a malfunction in the Engine Control Module (ECM), possibly due to data transmission errors. Could this indicate that the ECM itself is faulty and needs replacement? I'm increasingly frustrated with how much money I've spent on repairs without resolving the core problem. Any insights or suggestions for troubleshooting or replacing the ECM would be greatly appreciated. Thanks, J