1997 Buick Lesabre Would a dirty or bad MAF cause my car to shut off? The problem i am having is that when i start my car up in the morning, i drive to work just fine. i then drive around the property until about 5pm. when i go home, everytime i step on the brakes my car shuts off. another thing is when i drive on the freeway, if i am driving 55 and coasting, the car starts to idle up and down constantly. but if i take my foot off the gas then reapply it stops, but will do it again..