MB Frau. Its the throttle actuator starting to go. When its cold its ok,when your car is warmed up to normal operating temp. The throttle micropressor its getting mixed up. Eventually. you will start experiencing more of erratic and surging idles complaints. These 119 engine are notorious for this. also. If you never repl, looked into replacing your fuel pressrue regulator. When these engine warm up pressure drop,and if the diaphram in the regualator is defective, this could cause a stalling out problem.,You could be having 2 seperate complaints. This is just taken from my experience over the last 16 yrs working for MB

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500E Sold
2006 Mini Cooper S
Modified,pulley,injectors,suspension
2009 E350 Sport AMG package