Low Voltage Gremlins

2005 Toyota Sequoia 4.7L

Things I’ve replaced: Battery Alternator Ignition coils Spark plugs Valve cover gaskets Even did an oil change and the air filter

Son left the interior lights on and killed the battery. Battery was bad so replaced it. Car would die at a stop so I assumed the alternator was going bad. Symptoms persisted so I took a look at the ignition coils. Sure enough, cylinder 3 was covered in oil. So last night I went ahead and replaced the valve cover gaskets and replaced all the ignition coils and spark plugs. Test drive this morning and I’m still having issues.

Voltage gauge reads normal at startup but then after driving a mile, it drops at stops/idle. Driving down the road, and the gauge is at dead center. Things are better in that the car doesn’t stall anymore, but something is obviously wrong. Battery terminals are clean and all grounds and connections look fine.

Battery reads 12.3v when the car is off (makes sense given that it’s been sitting for a week and the test drive showed issues).

Turned the key to ACC and the battery reads 11.8.

Engine running and the gauge reading low, battery reads 12.1v.

I also got a P0101 while test driving this morning. No idea if that is somehow related.

Any help would be greatly appreciated. I’m at a total loss now.