I have an 83' 240D and lately it has become more noticeable when i slow to a stop and the car goes to idle my pressure gauge on dash drops below 2 and the car starts to run a little rougher, as well as my vaccuum pressure drops so the brakes feel different, etc. As soon as i give it throttle it picks back up but im wondering if something could be adjusted or if my oil pump is failing or any ideas?

Im afraid if i have to stop drastically fast my rpms will drop quicker and i will lose brake power while still slowing down.

 

On the 617.952s the lowest Oil Pressure limit is 0.5 Bar, so are within the norm.

Part of the idle roughness issue and idle Oil Pressure issues partly dependent on the Idle speed. Somewhere under the Hood on the upper Radiator Support Cross Member is an Emissions sticker that had your idle speed and other good information.

Another thing that can cause low Oil pressure is if the 2 little O-rings at the bottom of that Tube that is attached to the Oil Filter Cap need to be replaced.

Rough Idle can be caused by Air leaks in your Fuel Supply Hoses on the Suction Side of the Fuel Injection Pump.
If you have a Hand Primer that has a shiny Aluminum Body and a hard Plastic **** on the top they are a know source of Air Leaks when they get old and should be replaced with a new Style Bosch Hand Primer.

Start with simply looking for Vacuum Lines that are disconnected.
Next check the Vacuum Pump Vacuum to be sure it is not the Pump causing the issue. Ofen it is the Check Valve that Screws Into the Vacuum Pump is gunked up of has broken parts inside. That Valve is under where the Main Vac Line attaches to the Vacuum Pump.