John, no I never found it.
1. I bought a pressure guage on eBay, and checked out everything - no problems at all. It holds good pressure overnight, and jumps to exactly correct hi-and-lo-side pressures in an instant when the key is turned.
2. I replaced the IAC rubber hoses, checked all the vacuum lines, and it has good idle vacuum, about 17", which seems to be the norm for the 103.
It pegs the dash guage in neutral at 650 RPM.
3. I also monitored the EHA current during start and run at various speeds. I adjusted the EHA screw a bit, in both directions, and monitored the duty cycle - no effect on the chugging.
4. I replaced plug wires and cap/rotor.

So, as of today, it runs perfectly, after the initial few seconds.
Fuel system checks out fine.
Vacuum checks out fine.
EHA current and duty cycle are spot on at start, idle, and cruise.
Ignition is fine, as far as I can tell.

But to add insult to injury, over the winter, it started to no-fire on the first try. If you hold the starter on for 2-3 seconds, it will struggle to life.
But if you just nick the starter once, turn it off and nick it again, it jumps to life perfectly. EHA adjustment had zero effect on this.

Oh well, must be the flux capacitor.
Actually, I'm leaning toward something in the ignition? But, they usually fail the hotter they get. And it runs fine idling in hot traffic with the AC on.

So, onward to addressing that little R12 leak I found in the condenser.

DG