I'm having trouble finding the source of poor/no idle and stalling of my 1980 450SEL. Unfortunately I have been guessing and replacing components without a logical diagnostic plan. My first question is what type of CIS do I have? Some sources state that the K-Jet and the K-Jet w/ Lambda have a cast iron fuel distributor painted black where as a KE has an unpainted aluminum fuel distributor. Mine is aluminum and have a frequency valve mounted on the left and a O2 sensor on the exhaust manifold (one). Evidently MB stopped making the electronically-controlled CIS in 1976 why would it be called a KE? Could some one direct me on a sane diagnostic pathway? I have replaced injectors,plugs,wires, distributor cap,rotor, intake manifold gaskets and intake sleeves and throttle body gasket sleeve,fuel filter,checked and replaced vacuume connections. Fuel pump output volume and pressure are within normal limits. Hard start,poor idle and stalling persists. Any comments or suggestions would help. Thanks Spencer S.