Battery Light Flickering over 3k rpm

[07GOKRT]

Good Afternoon everyone,

I have an issue that I cannot find the answer to anywhere. My battery light flickers at speed of 70 to 75MPH that’s right at 3000rpm. It started doing this about 3 weeks ago. I will list all of the things I have checked and done. Hopefully someone has had this happen and found out the problem.
At 3k rpm the light flickers very faint on the dash. Under 3k no flicker. If I drive 65mph no flicker at 2800 rpm.
1. New alternator about 4 months old.
2. New battery 2 weeks old.
3. New serpentine belt 2 days old no change.
4. Checked Voltage 14.23 when running. I ran wires into the cab and hooked up a digital voltmeter. No change in voltage when light flickered.
5. Checked Voltage when over 3k and light flickering still 14.23 no change in voltage.
6. Checked connections all good. No change.
7. Here is the tricky one. When driving at night with lights on over 3k light flickers. However when I shut my lights off the light flickers more turn them back on and light flickering it ½ the amount of flicking. Note I do that briefly…lol
8. Now when I start the car cold. The motor goes up and down and stutters for about 10 seconds then purrs like a kitten after that.

Thanks
07GOKRT