I inspected my distributor cap the other day thinking that maybe that was the cause of my poor performance. Inside I saw that the contact points were corroded with blackish-grey stuff that came off with a file. After the corrosion was filed off, the contact points still don't look copper. They are still black. Does this mean I need a new distributor cap, or is it okay since there is no green stuff?

As the air gap increases from rotor to d/cap contacts, the coil has to work harder & this can cause the burn time(spark) to lessen, esp under hard accel. Cap & rotor replacement can save $$ over time.