Had my car for four years no problems until today.

It runs and starts ok, but under pressure above 3000 rpms it seems to be fuel starved, engine seems to die no power. Ease back for and all becomes right again.
Any thoughts !!

 

1st thing i would do is replace the fuel filter. That is one of the cheapest fixes on a Benz. If you lose power on the highway a little at a time and when you shut the engine off and let it sit for a minute, start it up and it runs fine and then cycles thru the slowdown/lose power trip, then sometimes a bad Cat Converter will cause that.

 

Fuel OK?
Fuel filter OK.
Serviced at correct intervals etc Plug change etc

...then I would go for the MAF Mass Airflow sensor.

You are describing typical first symptoms.

Guess you will have the CEL Check Engine Light on soon.

Try cleaning it first but this doesn't always work.

Stuart.