the problem you describe is the subject of a recall by Honda. the problem is with the ignition switch (the electrical switch on the back of the key cylinder that you put your key into to start the car). the ignition switch contacts get burnt and when they break contact the car stalls. It almost alwayus happens when driving down the road.
All 1999 hondas were recalled for this defect. the repair is to replace the ignition switch. all recalls are done at no charge regardless of the age of the vehicle or the mileage on it and regardless if you are the original owner or not. take your car to any honda dealer for the no cost recall repair.
hope that helps