Fiddled around a bit today, and cleaned up the poles in the inside of distributor cap. Tried a few times, and got the engine to start!! However stalls pretty soon after, usually it's hard to start again. Sometimes you can rev the engine all the way to red line, but sometimes it would stall upon attempting to revving it to keep the engine going. Battery got low from all that cranking before the engine really warmed up.

Two observations today:

1. Some black solids, from sand sized to say 3mmx2mm, came out of the exhaust pipe, now this doesn't look good...

2. The distributor end of the green wire (to ignition module) is cracked, I cracked it open while removing for inspection. However all connections seems still OK.

I will replace the green wire tomorrow, and see how it goes. Meanwhile any suggestions are welcome and appreciated.

Thank you all for your help and support.