Hesitation, stumbling

[RobertCrane]

I have a 79 spider automatic that is all stock. When the car has been driven for 10 to 15 minutes or more it starts to hesitate. If driving at 60mph it might start to skip. If at a stop light the engine will die when I start to pull away. Usually it will start again but not always. I have read about the problem with vapor lock and the fuel delivery but I do not understand why it is occuring if it did not happen when the car was new? or even when it was 10 or 15 years old?

[So Cal Mark]

I doubt it's vapor lock, but as far as the rest of the fuel system is concerned it's now 31 years old. Lots of things deteriorate over time including carb diaphragms and fuel hoses as well as ignition parts

[vandor]

Robert,

It could be a lot of things, and you (or your mechanic) will just have to test each component one at a time to find the culprit.
However, two things come to mind. First, remove the distributor car and check the condition of the magnetic pickup wires.
Second, install a fuel pressure gauge with a T connection into the fuel supply line (preferably just before the carb), and see what the pressure is with the car running, and what it is when it acts up. I've driven a lot of Spiders with a pressure gauge taped to the windshield