No gas pedal throttle response

No, to the coil. That has no control over charging system.

You had those other ECM's and that is part of the system check.

The regulator is inside the alternator. When you checked the voltage at the battery, did you also check for any AC voltage?

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Roy

HY: Generator/Regulator System

HY: Introduction See: Computers and Control Systems > Pinpoint Tests > HY: Generator/Regulator System - Introduction

HY1 CHECK THE GENERATOR CIRCUITRY AND OPERATION

Note:If the concern is still present after checking the generator circuitry to continue generator diagnosis.

Check for any generator related DTCs. Refer to Charging System, Charging System to diagnose any generator related DTCs.
Is the charging system diagnosed and repaired in Charging System, Charging System?
Yes

The system is operating correctly at this time.

No

GO to HY2
.

HY2 CHECK THE GENERATOR MONITOR SIGNAL

Key ON, engine running.

Access the PCM and monitor the GENMON PID.
Is the duty cycle between 5% and 97% and not excessively fluctuating?
Yes

The system is operating correctly at this time.

No

GO to HY3
.

HY3 CHECK FOR CORRECT PCM OPERATION

Note:When the battery (or PCM) is disconnected and connected, some abnormal drive symptoms may occur while the vehicle relearns its adaptive strategy. The charging system set point may also vary. The vehicle may need to be driven to relearn its strategy.

Disconnect all the PCM connectors.

Visually inspect for:
pushed out pins
corrosion
Connect all the PCM connectors and make sure they seat correctly.

Carry out the PCM self-test and verify the concern is still present.
Is the concern still present?
Yes

INSTALL a new PCM. REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Computers and Control Systems > Diagnostic Trouble Code Tests and Associated Procedures > Flash Electrically Erasable Programmable Read Only Memory (EEPROM), Programming the VID Block for a Replacement PCM.

No

The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.