Ok - thanks 77CVT for your reply.
I'm at work and set up to read the codes and got 33, 34, 36 aaand a 42222 what the - I expect a 43 not a 42, 43 is the EST - ie the module in the Dissy that changes the Pick Up (points) signal to drive the Primary Coil winding of the EHT Coil. Reading Manual. Ah haaa! the last time I did the Timing Light I disc the bypass or "Set Timing Connector", I must have left it open cct. No it was OK, but still had the codes - penny drops - disc battery - reconnect start codes again and sure enough all codes now reset. Start car - you can still here it running like a dog. Drive up street and give it some boot - still no codes but it is still missing and occasional backfire.
Now - 77CVT - thank you I have checked those items - the book also says check them as they are the most likely to cause issues. On ECM - yes it has a whole lot of stuff "HARD' programmed into it and you can change the chip to give other specs. But the ECM is only a Computer and can only give "X" if inputs "A ~ Y" have certain values. So a section of the memory is called "Block Learn" and as I said it sees what you are doing and sets the parameters for max power or efficiency or what ever you require - ie Dragging. BUT - this is volatile memory and if battery is disconnected the memory is wiped.