Hi Guys, new to this site, but was using it for research on my 98 ML320. Just changed plugs at 100,000 but vehicle still ran poorly. Tried cleaning MAF with alcohol but no luck. Then a friendly mechanic suggested Castle intake system cleaner. Took out sensor from intake tube, sprayed it thoroughly, then used low pressure compressed air to dry.
I cant believe how it runs now. Highway mileage between 24-25mpg. Was around 20-21. Acceleration smoother. Best part I didnt have to buy the new sensor I was ready to purchase.
Hope this has been helpful.
Thanks for all your help.