Update: very busy weekend left me with no time and no other options but to continue driving with it the way it was. Was not experiencing anything other than the low idle. Drive about 500 miles since Friday just keeping my foot in the pedal at stops.
Today I tweeked the mechanical idle adjustment screw on the back of the IP. Raised the idle back to around 650. So far no problems.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"