[tbirdtbird]

what is missing is an on-the-spot diagnostic session when the car acts up. You need to take another person with you. When it coughs or dies you need to have them operate the starter while you pull the coil wire and check for a good 1/4" blue spark to ground. If you get that then check for same thing at each plug.
When it acts up try different choke and/or GAV settings to see if it is fuel-related.
If it will idle at all when it acts up, but runs rough, use a plastic handle screwdriver and short out one plug at a time to see if all cyls. are doing work. If you short a certain plug and the rpm doesn't drop then that cyl is not doing anything.

Etc.

Since it is intermittent you have to be ready to jump on the problem as soon as it occurs. Is the fuel line pushed too far inside the carb? If so it can shut off the fuel supply.

These cars are actually very reliable but everything must be properly set up, and there is a learning curve for the eccentricities of the car, like there is for any old car.