Today latest Update:

Removed the MAF sensor and sprayed with CRC MAF cleaner. Put back the MAF sensor to its regular placement.

Ran the dm codes and still code 6 (faulty idling issue). Code reader in pin 8, no codes, pin 14, no codes.

Start the engine. At first, idling needle went up to 13000 rpm, then settled down around 8000 rpm. Pressed the brake, same results (8000 rpm). Put in drive, shifting was hesitating. The same hesitating goes in reverse as well. All shifts showed identical 8000 rpm idling at the same time pressed the brake between shifts.

Drove the Mercedes to the store. Driving was smooth, cruise control works.

Went home, turned off the engine and fired up the engine. Idling went very high around 30000 rpm. Pressed brake and shift to drive, idling went down to the normal range (8000 rpm). At the same time, oil pressure unit was hovering around the needle range of 1 and 2. Oil sending unit warning light on. When accelerating on the pedal. Oil pressure around 3. Smelled burning oil again, same location (source of burning oil is by the EGR valve tube or pipe).

Ran the code reader, same results as above, except pin 8, code 13 (O2S (Lambda) control system operating at rich or lean limit). Cleared the codes with code reader.

Next is to check the oil sending unit by the oil pan and checking the wiring as well. If necessary, I will get a new oil sending unit and to see if that would resolve the issue of oil sending unit warning light as well the floppy needle on the oil pressure unit (to stablize the oil pressure).

Also, will check the reasonance valve and throttle EA for vacuum leaks in the area. In addition, checking the wiring for cracks, frayed, etc.

If I cannot find the location and source of the oil leak near the EGR valve area while checking the oil sending unit and its wires, then I will take the Mercedes to the shop for oil leak diagnosis.

Stay tune for further updates.