Random stalling and dying

I had a similar problem. Found out it was a dodgy cable going into the electronic distributor. A few strands of the wires were broken and when the wires would get warm they would go high resistance. Was a real PITA to diagnose. I ran it like that for about 2 years before I could diagnose it. Suggestions - look for old wires, bad joints or loose connections, that's about all you can do unless it goes faulty continuously. Intermittent faults are the most difficult to diagnose so you just have to put up with them unfortunately until they develop further.