Do this little test - after cranking it, quickly check the ballast resistor on the coil to see how hot it is. If it is hot enough to burn your fingers it has failed (obviously take care not to burn your fingers!) If the coil looks original, replace both the coil and ballast resistor. There are plenty of OEM style coil/resistor assemblies on ebay but try to upgrade to a transformer type ignition coil as they deliver a more stable spark at higher rpms and the output voltage is also higher which improves burn of the air/fuel charge.

*the crank/start/stop and delayed start are classic symptoms of a bad ballast resistor. The coil will refuse to fire once the resistor has overheated and the cooling off time of 5-10 minutes is enough to encourage the coil to run a few cycles before it overheats again. Hopefully this is a solution for you...