The common issue on 119 engine secondary air codes is plugged passages in the cylinder heads. Not a nice situation.

Pretty easy to test for though. Run the second air test with SDS with engine warm and in closed loop. Pump runs and O2 sensor voltage must drop below 40 or 80mv (later cars go 40 early 80, this one probably 80). If it won't go 80 then one opens the vacuum line to the brake booster. If a sudden gulp of air there drives the O2 voltage below 80mv where the pump wouldn't then the airflow from the sustem is low. Verify check valve openning and cry.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician