Well, then it sounds like you have a lambda system that's doing it's job and the primary suspect is the catalytic converter.

But it might be interesting to measure the voltage from the o2 sensor at hot idle. You can do this by sticking a pin through the insulation into the wire and connecting your meter between the pin and ground. You should see around .45 volts.

__________________
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