Is the sensor plate moving up and down easily? If it doesn't move when you open the throttle plate, then the engine won't get any additional fuel. Maybe something in the mechanism is sticking?

Or you might have a huge air leak between the throttle plate and the mixture control unit, so that the air movement created when the throttle plate opens is not getting "transmitted" to the CSI via the throttle plate.

Also, take a look at the rubber plumbing for the idle and aux air valves for leaks.

__________________
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