apeters

Hi I'm new to these forums and looking for some advice/guidance. I've had a 65 289 for about a year now. It was running great for a while but I've been having an issue recently with it shutting off. Once I have it warm after about 10 or so minutes of running, the motor will shut off when I use any electronics (brake lights, head lights/high beams/ blinkers). This doesn't happen when right after I start it up, only after it gets warmed up. I've been working my way through replacing parts for some other smaller issues I've had but I have absolutely no idea what could be causing this... any ideas?

I'll post some pictures later.

Thanks