That was an important clue, Black smoke usually caused by faulty Fuel pressure regulator and O2 Sensor.
Sometimes faulty fuel pressure regulator contaminates O2 sensor,
Even you just replaced O2 sensor, it might be already killed by faulty fuel pressure regulator.
Anyway, you can try fuel pressure regulator first.
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.