I have a '78 Spitfire that we tore down and built back up over the past several months. The car is all together now and runs, but the engine will start shutting down after anywhere from 5 to 40 miles of driving. When it has died but is still moving, the accelerator pedal has no effect. If I push and release the clutch, say in 3rd gear, the RPM obviously drops to zero, but then comes right back and I have about 2-3 seconds of power. It has the original Lucas 45DE distributor upgraded with the Pertronix Ignitor ignition system, as well as proper coil, new wires, cap, rotor, and plugs. Timing is at 10 degrees before TDC. Carb is the original ZS 150CD that has been professionally rebuilt. Fuel system is clean and flowing a regulated steady 2-3 PSI. Voltage to coil remains steady. My personal thought is the Pertronix unit is heating up and cutting out (as electronics do not like heat), but I wanted to see what this community thought about my problem. Any help is appreciated!