My 1990 240dl is stumbling and shaking barely running. I have gotten a code 113. Changed the o2 sensor, cap rotor and plugs. The reason I changed the o2 sensor was because I checked it with a voltmeter and got almost nothing. I grounded the green wire and the car began to idle well. So, I said to myself I must have a bad sensor. After I changed the o2 it was the same. After more investigating I now realize The o2 sensor was reading correctly, the car is super lean. .002-.004 volts on the meter at 1500 rpm if I can get the motor to that speed. At idle the volt meter will read .8 volts but idle horrible. The ground to the motor is good, checked with a meter. I can not find any vacuum leaks. Can someone please help me. I need this car to commute for work. I am thinking maybe the computer next but I hate throwing parts at cars.