Have been doing much the same with my 87 300e recently and would like to add my 2c

First off, my car wouldn't restart after the engine bogged down during adjustment. I thought it might be too rich still, based on the X11 reading of 2.9v (78%) but after research in this forum discovered the mixture was probably too lean, no gas to ignite. Went back outside, richened up the setting and was able to start the engine and continue.

I had the same problem of adjusting the mixture trying to get some response at the X11 terminal and had much the same readings - 70% at KOEO and 77/78% at idle which I try as I might I couldn't change through adjustment.

Steve B kindly responded to my request for help last week and pointed out that there was not much use trying to adjust for lambda when there was no lambda sensor fitted. Doh! Don't know if that applies to your US model cars though but take a look.

http://www.peachparts.com/shopforum/showthread.php?threadid=99320

Perhaps you might also be interested in my fuel pump relay adventures.

http://www.peachparts.com/shopforum/showthread.php?threadid=98631

Have now been reliably informed (by my local dealership) that it is OK to use a relay for the automatic model (marked with kickd) in a manual, but not the other way round. In manual models, the 10th pin (87h, I believe) has no corresponding contact in the socket.

And for the kicker, I've hopefully traced my intermittent idle and hesitation problem to bad electrical connections at the ICV and now the EHA valve. Replaced the connectors and so far its running fine.

Hope this helps. Good luck

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1987 300e manual 250,000 km (sold)