cap and rotor?

it seems to me that about every 5 - 6 months i have to replace my cap and rotor. the cap points and the rotor both had alot of corrosion and it looked very worn and burnt out. i decided to check it today because my msd coil took a shit on me the other day and i noticed the car misfiring slightly here and there. the ignition consists of a msd blaster tfi coil, fms 9mm wires, autolite #25 plugs, stock dist. with a jegs ignition module. does anyone know what would cause this and what i can do to fix it? what kind of cap and rotor should i get? thanks

I always use a brass top cap and rotor and change it every other oil change, sometimes every oil change, depending on how the car has been driven. I'm just anal like that.

ok thats a good idea i'l try that and get a brass top and rotor. thanks for the help...