Is it possible you're not getting enough juice?

I had this issue a number of years ago.

I had a stock alternator. The issue just kind of crept up on me. Add the msd, add an electric fuel pump, add some more gauges and then, the alternator just could not keep up. Most of the time, mine would do what you're describing. It would not happen until the car was warmed up. The gauge would show that the system was charging good but, the battery was getting low.

Other than the tach, the car never did anything stupid and ran fine. After I would drive it for the day, back on the trickle charger it went; rinse and repeat and the same thing happened for years. The tach was old so; I thought it was just a little finicky.

I can't even remember what finally clued me in to the issue but, I installed a new, higher rated alternator and the issue never happened again.

Maybe check the volts on the battery after driving it? It doesn't take much for electronics to act funny.