Does this car have a turbo? You mentioned at high boost . What kind of boost numbers? What kind of RPM are you cutting out at and are you sure your just not running up against the rev limiter? If you have an engine light are you getting a code for the miss-fire . Should be a p0301-304 depending on which cylinder is missing . If its a p0300 then its missing anywhere and everywhere randomly . So lets assume its not just bouncing of the rev limiter it could be a bad spark plug or coil pack or plug wire . If the car is actually running a turbo are you using a hi octane fuel . If your running beyond the recommended red line you could be getting into valve float . If you could answer these questions I can help further