egmonster,
some of us are using both an internally resisted coil AND and external inline resistor to assist the internal ballast coil...edit- what the in-line resistor is really doing is reducing the input voltage to the coil to hopefully keep it from burning up.
What I think is most important is the input voltage the coil is seeing..This is measured on the (+) on the coil post, and the ground on your meter to a good ground like the engine block (the (-) on the coil is NOT ground.) - this needs to be checked while the engine is running, and while the alternator is charging (i.e., normal cruise RPM)
Then you can use Neil's calculator somewhere in this thread to determine if you think you need an external resistor.
3.9 Ω is pretty good, and higher internal resistance than most. But, if your input voltage to the coil is too high, it may not be enough to keep from frying the coil.
Hope that helps clear the muddy water a bit..I think we need more info from your set up for further diagnosis.
Just for a reference point..I have a 3.3Ω internally resisted coil, and a 1.63Ω external resistor in-line in front of the coil (if my memory serves me..
) This gives me somewhere in the 10v range of input voltage to the coil.