After alost 2 month of doing research on tryint to find cheap way to fix heistation problem in my 2002 ML 320 i finaly got it fixed today. I drove already over 80 miles and car runs great.
I didnt want ot spend over 300usd for sensor so thats why tryied for this long. Was not easy becouse the OEM is different from what i got: OEM is whole pice ( Air Mass Flow Sensor with the elements around it ),thats why cost so much. All you need to do is replace just a sensor, but MB is not seling it.
Here is ebay item nr 130058996103 - with all description. Guy is selling it for 105.00 plus shipping cost.
I am not trying to help this guy sell hes item.I am trying to help everyone on this forum with this relly enoying problem on their cars.
I hope it will help.

Here are codes i was getting on it:
P0174
P0173
P0172
I also had missfire codes for 2nd,3rd,5th,6th cylinder

After i install the sensor, i had to reset the codes with the Code reader. The light didnt go out and the codes remain.I did it again and then i had to remove the key from egnition wait 5 sec and when i started the engine Check Engine Light went out.

Good luck everyone and Merry X-mas

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1998 A6 2.8 Sport Pkg. - sold
2000 TT 1.8 T - sold
2002 C230K 42k miles
2002 ML320 68k miles

----- In US since Jun 2004 so still working on my English -----