with cars like these, anything possible in some ways, turbo's, coilpacks, plugs, filters, etc etc. But sometimes just looking at the basics can help. Think back to the days of the simple air, fuel, spark - its running rich, adjust the mixture screw on the carb - easy. But not so easy anymore i guess. But im having a similar problem of missfiring and the odd idle cut out and it feels like to much juice going through. All i can do is look at the basics and go from there - a small thought is, the boost solynoid ( dam, i always forget how to spell that ! ) is it doing the proper .5bar-ish then jump to .7bar-ish ? wondered if maybe it could be stuck. Thats assuming your ride is not a far from standard beast that is, and just a more standard version like my own.
Really hope you get to the bottom of it soon !