Got it! FINALY! So if you have the same problem I was having, (getting the particles to die over time) here is how its done..
Use the persistant property manager, make a new solid black solid. Use that sold as the layer map and use the Age feather and Older/younger than settings in the ppm to adjust the values of the particles over their life time. Make sure that the black layer is the entire duration of your comp. Also, this doesnt work unless you use a layermap for a particle. It will not effect standard particles.
I hope this saves someone the ammount of time it took me to figure this thing out!!!
-A