The key may become stuck in the ignition as a result of a failed ignition lock cylinder. Replacement of the lock cylinder should correct this condition.Google+
Car Problem Reports
Mitsubishi Mirage Key Stuck in Ignition Lock Cylinder
Mitsubishi Mirage Problem
Average Mileage: 115,500 mi (51,000 mi - 180,000 mi)
Visitor, 1998 Mitsubishi Mirage, 180,000 mi
Key stuck, will not come out, but car will start. Have to disconnect battery overnight and while at work/school. Also, car cuts off when at a stop.
Visitor, 1993 Mitsubishi Mirage, 51,000 mi
A metal tab (which I believe to be a part of the ignition lock cylinder) broke off and fell into the lock slider which is connected to the key interlock cable.