car stalls immediately after start! everytime! please help 96 mercury sable?

i have a 1996 mercury sable that i just changed the fuel pump FUSE and the fuel filter on because it would not start just crank. Now after the new fuel filter was installed it starts but stalls before it even turns all the way on! also, before i installed the filter it would start and run sometimes but would idle very low and rough. if anyone has any idea of what's wrong with my car i would appreciate the help so much. thanks!