Fuel Injectors - are they bad?

[08&09R56coupes]

On my 2008 R56 non-turbo car with 6 speed auto. I performed the injector test with my Foxwell scan tool.

It turns off the injector for a specific cylinder, while the car is running, when you activate the test.
I tested all 4, only one of them really made the engine stumble. The others sounded like a misfire, but not as bad as #3.
The reason I tried this is that my car seems to be running rich. The plugs are very dark, but not oil fouled. I get occasional white smoke and you can smell fuel at the tail pipe. Not a raw gas smell, but a heavy chemical smell.
I checked my cooling system, no oil and its holding pressure and not losing coolant.
No water and oil mixing in the engine either.
It is pinging when you hammer it hard on flat roadways.

I ordered an upstream O2 sensor to see if that is not functioning well, but I was wondering if anyone has diagnosed this problem before.
Any help would be greatly appreciated.