Okay, done about 250 kays since the panel shop, still using the iridiums.
We pulled out the plugs on Saturday, and all of them are perfect, no fouling.
The only time it misfires is when on boost, it idles fine, will happily rev out on partial throttle, however whenever under load it misses.
My feeling now is that it could be a number of things:
1. dodgy coil. Better plugs, maybe demand more from the coils, and hence only misfire under boost.
2. dodgy igniter? My guess however is that this would cause the car to misfire continually.
3. dirty AFMs. Would this cause misfire under load?
4. spark being blown out by boost. Iridium tips are very small, would the spark be too small and get blown out by boost?? I would have thought not, seeing that these plugs are only specified for GTRs and supercharged mercs
I may have to go back to coppers and try that