What is causing my 98 Honda to stall out?



I have a 98 Honda Accord, 4 cyl. with 160k miles. About 15K miles ago I had a complete tune up and the catalytic converter replaced. I consider this car to be very well maintained with regular oil changes, etc. On an intermittent basis for about the last 5k miles it will stall out as I am slowing down or about to come to a complete stop. What could be causing this? It has gone for a couple of weeks without stalling and then will stall out several times in one trip. It appears to lose all electrical power when it stalls. It never does it when the mechanic is driving it, of course.