KJ Laser 1.8 auto connected issues

[BlueyTruey]

My Laser stalled, then, aside from being able to select first on the shift stick there are no gear changes in the auto box. At the same time it started to blow black smoke and became extremely difficult to start, running rough with no power when accelerating, cooling fans running continuously and before starting the engine. The HOLD button cable was damaged and so repaired but no gear box response or dash light when reinstalled. ECU checked fine, injectors removed and cleaned at workshop, regulator replaced with low mileage unit, MAFS cleaned with MAFS cleaner, TB cleaned, plugs and leads all good, PCV valve and grommet replaced, ECU temperature sensor replaced. Each small fix has the car running a bit better and starting easier but still seems stuck in third and blowing black smoke with fans running all the time. Next step is 02 sensor replacement. Transmission tech originally couldn't get any codes to diagnose fault. Anyone had this or know of this issue which seems to be interconnected with electronics.