Hesitation When Accelerating Audi A4

Hello!

When i press the accelerator over 1/3rd, the engine hesitates like is got rich mixture. I changed the distributor cap because the old one was in a pretty bad shape. This improved the things a little bit. Next i removed the spark-plugs. No 1 & 4 cylinders were ok, but the rest were black, rich mixture black.
The fuel pump is pretty noisy, but i think is either the fuel distributor or the injectors...

Any idea?

Hey, do you still have the hestiation whenever you accelerate with your A4?

Reason could be a problem with your transmission or a leak in your engine.