I'm really have trouble with my 97 Audi A8 4.2. Fuel pump crapped out for I replaced that and I'm getting fuel to my fuel rails, and it turns over and idles but the idle is really rough it almost sounds like a vacuum leak, if I push on the accelerator it tries to die on me , (won't rev up) and if I leave it just idling the car will die within a minute or 2. Idles at less than a grand .. I do have a o2 sensor by the manifold under the hood missing but as told I could run my car without it just no idle control. Is this the reason my car is not running like it should right now? Any ideas?

That's a big part of it, yes. The sensor helps the car determine how much fuel to add to run properly.

Why the eff is the sensor missing??