Douglas,
In my case, the car would misfire on an irregular basis. It would cruise along fine for awhile, then miss for maybe 20 secs then run fine again. I don't know how long she had the wrong coil and ballast resistor she came to me that way. When I replaced the coil / resistor she ran much better. Then when I replaced the points, better again.
Chuck Bartlett
69 280SL
Chuck Bartlett
1969 Signal Red 4 Speed