If the idle still isn't working try gapping the points. It should be 0.45mm or so.
If that doesn't work you probably have an air leak, maybe even a bad crank seal. Spray some carb cleaner on all the joints between the parts of the engine. If the engine speed changes you have a leak at that spot. If you're getting lots of gunk in the ignition behind the flywheel, then the crank seal is probably bad.