Try this, unplug it for 30 mins, plug it in and start it up. Let it idle for about 15-20 mins (it will probably idle a bit wobbly over this period) then blip it a few times up to say 2/3000 rpm so the idle lowers and stabilises. Leave it to idle for a further 10/15 minutes after which the idle should be stable at 900rpm! Take it for a gentle drive, bring in boost after a few minutes, but gently ie don't take it to full boost across the rev range yet. Let the car cool and shut it off. Let it cool further and then take it for another drive, gradually riving it harder until you get full power. I did exactly that for my Mine's ECU, and it works like a dream. Looking at your problem I'd have thought it'd be ignition related but have you checked Dizzy, rotor arm & timing?