what a pain in the butt these cars can be, it idles rough all the time after cleaning the idle control valve, . I've changed out the front hoses, distributor cap and rotor was changed about 10,000 miles ago as was the fuel filter, spark plugs were changed to bosch supers about 50 miles ago as was the air filter, i love these cars but this is frusterating and i don't want the mercedes dealer to rip me off either, locally they are owned by the chevy dealer. any other ideas, i'm going to try spraying the hoses tonight and see if i get a difference. I don't know how long the wires have been in, so i am going to buy a set of berus so i will know. some times it runfs ok then you can hear it surge momentarily then goes back to normal ide, not sure what that indicates?