1999 W210 Occasional Misfire
 

Sometimes I will start the car and drive down the road. I make it to the traffic light and when it turns green get onto the highway only for the car to start to feel sluggish. I pull over and it struggles to stay on. I put pressure on the accelerator to try to keep it running. Sometimes it cuts off and when I start the car it no longer has an issue for the rest of the day. Sometimes the issue clears up without cutting off and I don’t have any more issues. One day before I left I revved the engine a little and got the issue to happen in my driveway to the point it produced a P0300 code for Random/Multiple Cylinder misfire. Any suggestions?

I'm going to assume it is a gasser?

How old are plugs? Any maintenance history?

Miles?

220+ miles. It’s a diesel not gas.

Change fuel filter/s.

Only diesel misfires I've had over 50 years has been because of fuel filter failure.

In addition to the filter recommendation, the fuel line connectors on these are notorious for leaking air and/or fuel. If you haven't serviced those yet, may be time.

I will get some new fuel filters, not sure when I changed them last. I think I changed all the clear fuel lines in 2022, how often should I change those? It looks like one of them is leaking. Would that cause a misfire that sometimes happened and sometimes didn't? No issues last few days.

Fix this first.