on a 1999 mercury marquis, then it will run good for awhile then do the same thing again. I had 2 snow tires put on the rear wheels, and when I was on my way home, the car would get up to about 50 mph,and slow down to about 20 mph, then it would run good again. Is this caused by the speed sensors? It does this off and on. Can you tell me what and how to fix this problem? Don
Jan 2, 2012 at 11:59 AM
