Try to check the throttle setting, the throttle should be totally close, when idelling. there are tro micro switch, one of them for the KE computer, and one of them is for the ignition computer, in idelling position, when the throttle has closed, both of the switich should be 'close' as well.

I fould problem with mind in starting ( mind is a 300E, and after pin point the problem and replace some parts from in the injection system, finally I fould that, is just the throttle setting playing with me!