Three times now within the last 30 days or so the car has died when shifting into reverse from park. I shut the car off and restart it to try again, which usually works. When I shift into reverse it sounds rough and starts to idle low then just dies. It always has been a little rough shifting into reverse. Normally when I do it takes about 3-4 seconds to engage and when it engages it jerks a little. What would cause this?