2000 LINCOLN Towncar started gradually making a sound and also jerking mortion: about over 2 months ago and is slowly increaing overtime. Hs been inspected by gargage 3 times without a clue.
Carburetor with dirty flip has been ruled out. Best guess was thought to be related to the gas process. Starts ok, but the jerking starts and stays 36 mph until about 44 mph - then stops. Drives well up to 55 mph without problems. If have to stop, then the same will repeat again. Car has 189,000+ miles.
Have had problems with electrical system last fall.