Hi guys, I have an MB6 with nearby 100K Miles but I have a little problem. Engine idle is Ok, but when I try to stay the engine at xxxx rpm without moving the car, rpm's are unstable, it ups and downs lightly (100-200 rpm of constant variation). What could be the problem? Rotor, Cap, Coil, Ignition Module, Wires, Fuel Pump, Injectors? Thanks!