I'm not sure if it's caused by points being gapped too wide or too close, but basically the spring that closes the points becomes weak over time, and as the distribtor turns the points open too far, then slam shut, which causes them to bounce open again (like a rebound). Sends too many sparks through the distributor and makes the car run like cr*p at high RPM.
New points, gapped right, and the correct initial timing should be the ticket.
If not, let me know ... I need to learn something today!
