I don't know what big black connector that would be that leaks fuel. It's common to leak engine oil from the control rod sensor electrical connector inboard of the engine shutoff actuator. Not much you can do other than clean the area, smear RTV, let it dry completely before starting the engine, and sacrificing small animals. Leaks just below where the injector lines attach to the IP are typically cured by replacing the delivery valve seals. It can be done as easily in the car as out of the car but it's easier in the car with the crossover pipe out of the way. Make sure the injector lines are secured along the way to the injectors or you'll be replacing them soon enough.

Sixto
87 300D