[tirwin]

Originally Posted by mysocal911

And while cruising under a light load also for emissions.



They all vary the same parameter, i.e. the fuel quantity, to vary the AFR ratios under differing conditions:

1. Carbs use different jets for variations in fuel quantity.
2. CIS uses movements/adjustments to the sensor plate for variations in fuel quantity.
3. EFI, e.g. Motronic, uses air flow thru a sensor (AFM) or air mass flow thru a sensor (MAFS).

Yes, I understand that. It wasn't clear what the problem was or what type of fuel system the car was. The OP has clarified and I believe has his answer.