Had the mechanic check a lot of things now including the timing and compression and all is normal. But he found something - corrosion on the wiring and plugs that connects to the engine computer. Says it looks like it may have been flooded.
Cleaned it up, fixed the wires and says car runs perfectly in the workshop. Now for the moment of truth...roat test. I'm praying it'll be good otherwise reckons computer may need replacing.