I have a 1985 Camaro with a tpi. i was driving and car shut off instantly. no sputter. someone told me fuel pressure regulator because the motor flooded and got into my oil. changed the fpr and oil = no differece. gave it a new coil, plugs and wires. unplugged ecm and MAF sensor. Charged battery, plugged it all back in except MAF sensor. Started up with some throttle. idle jumped around, then it died. i started it again and eventually it idled by itself. so i plugged MAF sensor back in. tried to give it some gas and she fell right on her face and died. no i cant get her to start again. just cranks and re-floods itself.

 

I would try the ignition control module inside the distributor. When those are bad they tend to shut off or act wildly when warm. Allow them to cool and they work for a short duration before crapping out again. When they are going bad they cause intermittent sputter and stall akin to a loose ground in the ignition system. Check the grounds at the back of the cylinder head to ensure they are still tight and the wires are ok.

EDIT: yes a parts store can check the ignition control module but I have seen the tester give so many false positives that I just don't trust it anymore.