The car is a 1995 E320 with a 104.0992 engine. When I start the engine is starts immediately and runs rough, slightly shaking the car. When I accelerate into the 30 MPH range it lags and fails to accelerate but does not stall, and there is no engine light to indicate there is a problem.

My initial thought was that a cylinder is not firing and three weeks ago I had replaced the spark plugs and spark plug wiring. Until today, the engine has been running without an issue, and I did recheck the plugs and wiring for lose connections.

Based on other posts, the mass air sensor, the fuel filter, or the injectors could be the cause of the issue.

I am looking for advice on how to isolate which one, other than buying the part and trying it. Any leads would be greatly appreciated.

Cheers.

 

you can simply unplug the Mass Air Flow meter and if the car idles smoothly, that's probably your problem. The fuel filter should be changed on a regular basis, so changing it now would be a good idea. I doubt that you have bad injectors. A vacuum leak would be a good thing to look for as well.

 

After many tests I took it into the local mechanic. He noticed that fiddled the wires in the wiring harness whose destination is the spark plugs for cylinders 1 and 6, the issue went away. After removing the sheath around the wire the short was located. Ultimately I will need an new wiring harness.

Thanks