S124 1995 e320 high fuel consumption

[diesellac]

Hi all
Diesel guy here who went to the "dark" side

I bought a winter beater 1995 m104 w124 wagon. No records, it's the usual deferred maintenance junker. The price was right and I didn't want to expose my sdl to road salt.

I'm not familiar with the M104, but I am mechanically inclined.

So far love the car. But I've been getting 13mpg city (suburbs). Looking online I've seen people talking about ranges from 15-20 mpg city.

Is my mileage normal or low?

The car has a slight shake and maybe a slight missfire at idle. That could be the motor mounts though.
When accelerating and at speed the car is smooth as silk.

The car has the updated wire harness.

So far I've changed the plugs(copper non resistor plugs) and the air filter and gave it an oil change.

My to do list is
clean the maf
Clean the throttle body
Check the vac lines
Change the O2 sensor

What are areas in the engine can I test/look at?

Thanks for any input.