well today my head gasket, cam seal, and valve cover gasket were replaced and when the distributor cap was taken off, it seems as if the rotor wasnt tightened all the way when i did my tune up a few months ago, so one of the metal contact posts (dont know the name) was bent back, with a lil bit of metal shavings.... and the rotor was slightly damaged from the side... dont know if this has anything to do with the crackling noise though...