Engine randomly stalls and will not restart upon entering on-ramps. Automatic transmission randomly fails and slips into limp mode while accelerating from stop lights or accelerating into highway traffic. This issue has caused numerous light rear end collisions with other vehicles following too closely when the transmission malfunctions, causing the other vehicle to impact the rear bumper of the 500L. I had to have the vehicle towed out of traffic because it would not restart or move under its own power