"The tach drops and there is an associated loss of voltage at the coil."

It could still be RSR related, even if new. Such as a funky RSR coil ground connection on the inner fender above the battery. I had that problem on my '93 Regina, where the RSR controls just the injector voltage. On your turbo it also controls the coil voltage. It was intermittent and possibly temperature related.

I would clean the tab-to-body contact surfaces, as well as ground wire connections at the tab.

As a test, try jumpering the 2 heavier wire connections at the RSR harness connector to see of the problem goes away. That voltage will still be controlled by the ignition switch, so the battery will not get drained with engine off.


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.