Yesterday as I drove my 240z home from the upholstery shop the tachometer took on a mind of its own and the car seemed down on power and running rough at idle.  Once I got home I looked under the hood and immediately saw my coil was leaking oil.  Worse yet, it looks like it has been doing this for awhile, how did I miss this?  Anyway, I have a new coil on the way but also wanted to test the ballast resistor.  With the car running, if I ground the negative lead of my digital multi-tester against