We had the same on our 998, changed everything (rebuilt carb, changed to a spare 65D dizzy, new electronic coil....) Still couldn't cure this until one day we decided to start again. Fitted a coil from another supplier and bingo... Knocked that wall down, will now hit motorway speed
Coil from another supplier
I've tried 3 coils dude, all the same problem after wards, 4th at 60mph
Ok, does the car have a review counter fitted? When it misfires does it make small bounces(+-100rpm(fuel)) or larger bounces(500 to 1000 rpm (electrical))
i took the rev counter off and tried down the duals again with no look dude