My 300E sluggish too...
I have replaced the cap, rotor, wires, plugs, fuel injectors, O2 sensor and OVP so far and no change. It's like the car has an intermittant vaccum leak which isn't possible in my opinion, unless there is an air valve that is opening and closing letting atmosphere into the intake manifold. If it was the fuel filter then it would do this all the time... right? I'm not sure if it is the fuel filter but what the hey, I've replaced everything else... I will check my coolant temp sensor too.