On a 2000 lesabre 3800 engine seems to vibrate slightly at Ideal, but at about 2000 RPM the vibration seems to cycle smooth to rough about 3 times a minute going down the highway. It causes a minor shudder of the car. It still has plenty of power and gets good gas milage. Any Ideas what it might be? I have and an extended warranty on the engine & drive train. The car hasd 69K miles on it.
Thanks Bill