Help with code P0519

[Noturbuddypal]

I'm having trouble fixing this idle air control check engine light. Here are all the things I've done or replaced.

2 new idle air valve (not OEM)
2 new neutral safety switch(not OEM)
new throttle position sensor ( properly tuned )
new MAP sensor(not OEM)
new EGR(not OEM)
new 02 sensors ( both OEM)
cleaned throttle body
cleaned PCV valve
idle relearn
adjusted throttle cables
vacuum smoke test ( found one small leak and fixed)
contact cleaner in all connections
cleaned all grounding connections
its been a mixture of me working on it with my limited knowledge and been to a reputable shop. The shop originally put in a new alternator, battery, and battery cables because of a battery light on the dash along with some CEL codes. However they put in a faulty alternator and I drove it home while the voltage was slowly dropping. I was so close to home so did my best to limp her home but battery voltage was seeing 7 volts before I shut her off in the driveway. Towed it back to the shop and put in a working alternator and no issues since besides this one code P0519.I have seen

The code seems to come on after warming up and driving about 40 miles then at some point when I let off the throttle to come to a stop for example the code with light up. It will eventually go away after some time, just to come back.

Not sure where to go from here in trouble shooting and been just throwing new parts at it or having the shop do their best to diagnose not sure where to go from here.
My thoughts are its an electrical issue, or maybe the ECU was damaged from the low voltage?

[20Baja06]

Assuming N/A here.

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Past that, you might check the main relay is functioning properly, that all pins in the connector are fully seated, that the wires are not broken from the solenoid valve to main relay or the ECU.

If all else checks out, it could be the ECU.