truegdc

I have a e250 w212 auto I have noticed when stationery from a fresh morning start, the car would seem noticeably louder, when colder mornings occur, it also seems that the idle needle seems to bounce, but only from idle upwards rather then down slightly with a small judder in the car when does it, also it Will seem very sluggish loud when driving, when it's hit the idle normal temp it seems to quite down and become smoother, in addition when taken on a long motorway drive the car seems to drive a million times better, when warm it's drives like brand new perfect steering sharpens up feels likr it should, now this issue happens sometimes randomly sometimes consistently, now and again I will start her and she will drive spot on cannot get my head around it advice would be so helpful to round it off deffently feel the cold weather has a impact on the car somehow

Mud

I think you'll get a lot of guesses, but this is a good opportunity to get a scanner if you don't have one to see what's happening as the engine goes from open loop to closed loop. They are relatively inexpensive - I have the MB ICarSoft scanner as well as a Konnwei 850 scanner. They can provide real time data streams and the ICarSoft scanner can access the various MB vehicle modules. They also help to narrow down possible issues so you're not just buying parts to try. Maybe someone has had similar troubles that can chime in.

Hopefully it's something simple but I don't know anything about how many miles on the car, has it been maintained regularly, etc. I assume you're not getting a CEL but codes can still be stored.

cocobeex

What year and mileage on your car ? Try to get tools to scan your car.
See if it shows some codes.

I had similar issue, The car felt different everyday when i drive it.
I couldn't figure out what is the issue. I thought it was the tune. Or Spark plug, coil pack...etc.

But it started to surge on highway when cruising, that's a sign of not enough fuel supplied.
After i replace my fuel pump, everything goes normal again.