I almost have it. Previous owner installed a big bore kit and cam and the car simply would not run with the 1970 Brain Box. Seredipity led me to try a 72 brain box and things got under control. Fuel pressure stays at The manifold pressure senseor also had to be cranked way rich (a whole half turn) and now the car runs beautifuly and gets aceptable 20-25 gas mileage). Except....

It continues to idle rich (which is something I'm definitely not!) This becomes a problem in stop and go traffic when the plugs start to load up, the idle drops and becomes lumpy.

I've thought about tandem pressure sensors (I have a spare) and setting one to factory mixture, switching automatically to that one at idle. But that's complicated and inelegant. I know there is a circuit in the brain box dedicated to idle mixture and I've played with that. My situation seems to have overwhelmed its capacity to compensate. Could I add some resistance to that, or substitute a different rheostat? What about that thing IPD used to sell. Would that help me out? Am I missing something simple, like timing?

Appreciate comments from people knowledgeable of D-Jet electronics.