I have a 2004, C230 Sport sedan, 6-speed manual, with about 65,000 on it. I drove it about 100 miles and then parked it for three days. When I started it up, the idle is very rough and the engine wants to stall. At speed, it runs fine. However, as soon as the throttle closes, you feel the engine speed drop dramatically as if the engine were shut off. Otherwise, the car performs beautifully. What do you think? New fuel filter? Clean the throttle body? By the way, the check engine light came on but there are no malfunctions shown on the computer.