My 2002 Impreza quite often will not give up the key. When shutting the engine off (car in park), the key sticks in ACC. It can be started and driven but again on stopping it won't give up the key. Or it does. It used to be a rare occurance and always with my key, not my Wife's. the problem is getting more and more frequent. Jamming on the brake pedal used to make a difference but not anymore. It doesn't do this all the time, but we never know when its going to happen. Help!!!