Volkswagen 2012 Tiguan water and black particles coming out of exhaust

I recently bought a 2012 Volkswagen Tiguan.

I have many problems with it:

1. Engine idles kinda rough

2. Engine usually spits out a good bit of carbon particles and water once the engine gets up to temperature.

3. There is some hesitation on moving off and the engine tends to stutter while idling or slowing down.

4. Took it to a mechanic, did a diagnostic and said that the following error came up: Oxygen Sensor bank 1 sensor 1

He also noticed some oil leaking from the upper engine cover gasket seals. He said to replace 06H 103 483C and 06H 103 483D.

I would like to know if replacing these seals and the sensors would stop the rough idling and the carbon dust coming out the back?

And should i go through with the hassle of replacing the seals or just get rid of the vehicle. I would be grateful for any advice!