If your throttle/thrust/micro switch has failed, unplugging and replugging will not help. You need a new one. Do you know, for sure, whether it is this switch, or the IAC, that was the probnlem?

For emissions, Techron helps; can't comment about other additives. Just make sure there is none of it left in the tank when you get the test, or it will send your HC numbers off the chart.

High HC can be caused by of incompletely burned fuel, or piston rings that are not sealing. AutoRX will help with ring issues, but not quickly.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black