Re idle stumblingWhat else do you think could be causing it? The engine is stumbling at idle too, like it’s missing a beat. The cap contacts are clean, rotor and points look new, plugs are good, wires are good and timing is rock steady at 12 btdc.
Have you checked with a vacuum guage .
can troubleshoot a lot of problems ieburnt,sticky leaking valves etc

Quick Tech: How to Read a Vacuum Gauge to Pinpoint Engine Problems
This article is packed with pictures to help you use a vacuum gauge and read the results to troubleshoot engine problems.

