I've been chasing a problem with my W5 engine since I bought the car 8 years ago. It would start and run just fine but every now and then it would just die. It even did this on the Club Tour out of Santa Rosa with our current President on board! I cleaned the fuel lines, installed a filter, rebuilt the carb, replaced the points, condenser and coil, checked all the wires, etc. Still if would randomly quit on me. Usually after I had been cruising for a while.

Today, I was driving it and a fellow told me his Dad as a teenager would switch the gas and radiator cap on Model T's and they would quit running. (They are interchangeable but the gas cap is vented and the radiator cap is not.) Then it dawned on me to check my after-market gas cap to see if it was vented. It was but it looked the worse for wear. On the way home, the engine started to stall. I had to really rev it up to keep it running. I had my daughter hop out and remove the cap. Sure enough, the engine recovered. So this could be the answer to my mystery.

Do You own a car built by Durant? 1925 Star Touring

Vince, Considering your previous actions to remedy the problem, you have definately solved it. This not an uncommon failure but one that is almost always misdiagnosed.
I've been there also, and it took a while to solve the problem. Generally, you can tell an electrical failure from sudden stopage, or, a fuel failure from gradual stoppage.

A couple of years ago, my motorhome showed symptoms of fuel starvation or vapor lock. It would stutter, spit, and cough to a stop. After a minute or so it would restart and run a while longer. The culprit turned out to be a failing ignition coil. This diagnosis took about 1500 miles and three repair calls!