Mine stalled in a similar way when the AC compressor kicked in while test driving with the ECU only hanging in the wire harness - the current draw became too high. Finally concluded that the ECU casing needed body ground. The problem was repeatable and the first bank injector code was set every time. My ECU however was fried even before that event but I also had (very) occasional rough running after warm starts, always cured by an immediate restart.

Checking grounds is easy and often recommended as a first step. There are a few in the connector (ECU-engine block and ECU-body) but my advice from experience would be checking the ECU casing - body 'connection' first. There also are a few main ground connections on the engine (brown wires at the rear of the head, difficult to see) and between engine and body (blue wire, originating from the negative battery cable).

Never touch anything without first disconnecting the battery power line or appropriate fuses, though. And don't rule out the ECU as the faulty component because of the lack of codes and the - mostly - perfect running car. Mine never returned any codes at the rough running occasions.

/Martin
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65' 121, 73' 165