Rick;

I does sound like you have done all the right things from your listing of the pre-conditions...and like C1800, the first thing I thought of was the influence on mixture, of the two thermal sensors (Coolant Temp, Intake Air Temp). You also did not mention to what extent the Cold Start Valve was checked for possible leakage/weepage (which at Idle would make more of a difference).

You should be able to set the Idle...from '71, the CO Adjustment Pot was added to the ECU, but that can only be used to adjust Idle CO, when Throttle Position Switch is adjusted correctly (first!), and 17(Idle) has continuity to 14(Chassis) at Throttle shaft fully closed (shaft CW). (Ref my notes on the TPS here: https://www.sw-em.com/bosch_d-jetronic_injection.htm#reference_information_tps )

I also agree with C1800's recommendation to visit the https://jetronic.org/en/d-jetronic site and learn from all you can from the info already there, and possible posts and dialog with Dr. D-Jet (Volker). He is a highly experienced expert on the system!

I am currently in a '73 ES recommissioning mode, so would like to ask who checked your injectors for you, ask about your experience, and if you recommend them...I need to have this service performed also, so I know where I stand with them...

Please let us know how you make out!

Good Hunting!