I have a 96 Chyrsler town and country. I have ahd many problems with the electrical sysytem, the alramset light goes on and off, the service engine light is on and won't go off, and mow and again the brakes will go to the floor and the days later be fine. Most recently the car is very sluggish and sometimes backfires and it idles very rough feeling like it will stall. What could it be?