If it's like the 380, there is a coolant thermo switch on the back of the engine. If you pull off the connector and bridge the contacts, you are simulating cold running.

Again on the 380, the lambda is controlled by an oil temperature sensor.

But I agree that with an idle that high you are probably not getting any voltage to the valve, or the valve is stuck open.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe