stalling

I have a 75' Dart Swinger w/ the origional 318 2-barrel. My issue is that about once a month while i'm driving for a few hours and come to a stop light or slow down for a car that is turning, the engine begins to stumble then shuts off.It will start right back up and when i put it in drive and start to take off it stumbles really bad and then eventually it will go away. It has the factory elec. dist. new ecu box, new voltage reg, initial timing is a 10 deg. The fuel filter shows no sign of rust or any thing else. Not sure of the fuel pressure.It has AC Delco plugs that are gapped at .035in. Also to note it does fine from my house to work which is 15 min. away.
Any suggestions?