1997 Ford Taurus engine problems

My 97 ford taurus sho v-8, the service engine light was on, now you can start it and it will drive some and then die, when you try to restart it it doesn't want to start. Yesterday I started it and let it run for almost an hour in the driveway and it never died, but when you try to drive it it wants to die and has a rough idle. I changed 4 of the 8 plugs cause I couldn't get to the other 4 and I have a fuel filter to put on it. I need help with this car it is too nice to be letting it set like this. Thanks