While driving on the freeway this weekend at approx 75 mph my speed suddenly dropped to 65 mph and had a slight vibration. It just seemed to be off a little. I pulled over and found that my car was idleing very rough. I checked the engine for anything out of ordinary, but found nothing. So the car runs ok when fed gas, but the idle is rough. However the car doesn't die. Also when starting from a stop is really slow and rough even when given lots of gas. Please let me know if you guys have any ideas....thanks...Paul.