Disconnect the car's battery cables, remove the spark plug cables and boot covers, and remove the old spark plugs. Next, put in the new spark plugs, attach the boot covers and cables and reconnect the battery cables.
0.050 or 50 on a coin looking gap setter you get from any parts counter. I believe this to be true but look for a sticker under the hood.It should have a lot of small print but you may find spark plug gap spec..
check your spark plugs they could fouling up or gummed up enough to spark for a while then as they heat up become worse. a lot of common problems with engine stalling can be directly related to plugs or coil etc.