This is not making any sense. If you went FOUR turns CCW on the mixture you would have completely leaned out the system. A half-turn in either direction is a HUGE adjustment.

Please do some research on the Forum on how to set the mixture correctly with the duty cycle reading on a multimeter, or at least get a CO reading at the tail pipe.

I think what is probably happening is that you have a one or more bad injectors, or a bad fuel distributor, and that you are not getting enough fuel at idle to one or two cylinders. But it's hard to tell until you can give us some baseline data.

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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