97 2WD 4.3L Blazer is burning through the rotor which is leading to a miss. Replaced it just a few weeks ago with cheap auto zone part and it's already got a bad burn again. Replacing and doing a tune up today but wondering what is the cause of the burning. I'm guessing it's shorting to the distributor body, but not sure how to trouble shoot and resolve.

Photo of the burnt rotor. http://imgur.com/gallery/Yrr9D