Spare part lottery II

Action taken (Apr 12 - 20, 2013)

• Distributor cleaned, pulled out and cleaned some more
• A lot of dust, rust etc under the distributor cap
• Also, there were some mysterious black flakes on the distributor shaft, but they didn't seem metallic. They don't react to a magnet, and break when you crush them with your fingernail.
• Ignition Control Module (ICM) in the distributor replaced (Standard Motor Products LX340)
• Ignition Coil replaced (Standard Motor Products DR37)
• ECM & its PROM chip replaced (original part, ordered from an eBay merchant in California, pulled from a 1992 Camaro, )
• PROM version is "AXKT", while the original was ANTT. As far as I know, AXKT is just a compatible upgrade.
• Battery negative terminal connector replaced
• The threads attaching the cables to the old connector were gone, so this might have caused some contact issues
• Grounding cable between battery and chassis replaced, contact point in chassis cleaned
• Grounding cable between battery and engine block was left in place, looks "ok"
• Battery terminals and connectors cleaned
• Wires to the Heater / AC blower motor disconnected
• Wires to the AC compressor disconnected
• I don't know what condition the AC is in, at best it's very low on refridgerant

Results
I had hoped that blindly replacing most of the ignition-related parts would take care of this problem, but the same symptoms that I had last fall are still there. I think things got a bit more reliable after I fixed the battery contacts and disconnected the heater/AC blower motor, so bad grounding and that worn-out motor were probably at least part of the problem. Still, this only lowered the frequency at which the symptoms occur.

I made a test drive of about 9 km today (5.5 miles), and the car died / SES'd maybe half a dozen times.

Other
Next up, I'm looking at

• Replacing the distributor Pick-up Coil (since I already have a new spare part)
• Replacing vacuum hoses
• Replacing the whole distributor (at about the same cost as all those distributor parts above....)
• Replacing the grounding cable between battery and engine block
• Checking / replacing the cable for the VSS (Vehicle Speed Sensor) 
• Replacing that 8th plug...

And possibly

• Checking the fuel pump wiring
• Replacing the TBI injectors

If none of this helps, it looks like I'll have to switch my brain on, do a bit of homework and actually try to diagnose the problem in a structured way.