2001 Honda Civic car dies while I am driving

My wife got stranded at the gas station yesterday because the car would not restart so her friend came and jumped the car which worked good enough to get her home. I have owned the car for 3 years now and have not replaced the battery so this morning I went and purchased a new battery and installed it, right after the install the car started up like new. Wife drove it all day around town and absolutely no problems. Went to go to work tonight and I got 3/4 of the way there and the car just shuts off while I'm driving no slow dimming of the lights or anything. So I figured the alternator was dead. This morning I went to leave and I tried starting it again and it fired right up. Then just to die the same way about 3/4 of the way home. Both times it died right after I put the clutch in to stop at a stop sign. If anyone has any ideas please help because this is our only car and I need to get it fixed quickly