I have a 75 Maverick with a 302. When it is driven for about 15 minutes, it will just die. If you let it sit for a couple of minutes it will start again. I was suspecting the Duraspark box, but I thought these either worked or didn't. Has any ever had a box act like this?
This symptom will also occur due to a dirty/clogged fuel filter. Once the car dies and sits, the trash will settle and again allow fuel by
If you decide to buy a new module stay away from the cheap ones. Expect to pay about $80 then you want have to carry around a spare. You get what you pay for. A bad coil when hot acts like what you're describing also.
I've had two modules fail after running a few minutes and pop's 79 Cougar did same when it was maybe four years old... In all cases they would start again after a cooling off period...