300SE Idling.

I have a 1989 Model 126 300SE ( Engine 103.983 auto) which has recently started mis-behaving on start up. Even on warm starts it frequently rev's at 2000rpm and does not drop back to the normal tickover of about 650. On
other occasions it will go to about 1200rpm and only occasionally will it idle at 650. Sometimes I can start up and, if it runs at either of the higher levels, I switch off and re-start to the correct rev's. Also sometimes I can give about 25% gas on the pedal and it will start correctly.
I've checked that throttle linkage is not sticking and have cleaned the air flow sensor plate and housing and checked that it's centred and free moving. Where do I go from here?
I'd really appreciate any suggestions.
Ray Rackham
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Ray,
I had the same symptoms on my 1991 300SE. It turned out to be the motor mount (of all things) on the throttle linkage side. It had collapsed just enough to interfere with the throttle a tiny bit.
-Tony

correctly.
air
moving.
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Thanks for the response. I'll re-check the linkage. Anyone have any other ideas?

rev's
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