The Carlsson hideous missfire now at last seems to have been be cured by replacing the Air Mass Meters. I you have a mis fire and changing plugs and then trying a new DI unit fails, try the air mass meter. I got this suggestion from Alan at BPV in Slough. Hagstrom Saab eventually got the right a.m.m second hand and bingo. Bambo, it seems I no longer need the parts I previously mentioned>
Julian