After countless hours of searching for an answer on the internet, I cannot find a likely answer so I'm hoping to find an answer here.
Background: A while back my B5 Passat developed a whooshing noise near the intake manifold/throttle body when the accelerator pedal would be pressed gently but quickly. The RPM's would also drop below 800 and the car would nearly stall but the RPM's would quickly go back up again. This was accompanied with low power and torque. I suspected it could have been the Intake Manifold Gaskets, so I replaced them with some Brand New Genuine VW. However, the symptoms had still been present. Not long ago I've also noted that the Passat has a very high Engine Oil consumption, can't exactly say how much but it's quite a lot more compared to what I had before I removed the Intake Manifold. Furthermore, the RPM's also drop and return to 800 when the A/C is just turned on or when the Power Steering is activated.

I've also realized that the Intake Manifold has a high amount of Engine Oil present, which I suspect is where the Engine Oil is leaking. But I do not know the reason for it.

I've also read about the Suction Jet Pump near the Throttle Body, but I'm not sure whether that is the problem.

Any help would be appreciated,
Thank you.