INTERMITTENT IGNITION ISSUE
Is it possible that there is an intermittent short in the ammeter, ignition switch, bulk head connector (which looks fine), engine wiring, etc? I believe the ignition system is properly grounded, including the distributor hold down clamp.
Answers.
An ammeter short, like any short to ground, will take everything out. When the short is broken the battery will want charging. If this happens you'll see the recharging on the ammeter.
An ammeter connection that is loose will simply cause an open circuit. The engine will likely continue running.
Glance at the ammeter when the engine misses and it may tell you something.
Ignition switch or its connector. Yes - its possible either short or loose. Short is when power goes from the supply to ground bypassing the equipment it is supposed to run. A break or loose connection is an open circuit. The electrons go nowhere.
Bulkhead. Same as answer as with the Ignition Switch.
Engine wiring. Ignition Run circuit (J2) with blue wires. Same answer.
It doesn’t seem to me that a bad alternator would behave in this manner or that it is fuel related. Since the problem only lasts a second, a multimeter wouldn’t seem to be useful.
A bad alternator will show up on the ammeter.
The needle will swing to discharge indicating the battery is suppying power when the engine is running. That's wrong. The alternator is supposed to supply power when the engine is running.
When the alternator is supplying power, the needle points straight up or shows battery charging (if needed).
I would not rule out fuel system, such as plugged idle passages if this only happens at low throttle. 2000 rpm, at steady 40 mph, could be relatively low throttle depending on gearing and tires.