Hi guys, I have been having an issue with my focus st 2009.
When I drive the car fast ie over 5000rpm then the engine management light flashes and the car starts to misfire. But if I pull over and switch the engine off and start it again the problem is gone. I have also check fault codes with bluefin which says no dtc found. It doesn't do it all the time it's only done it once about 6 months ago and then it done it again tonight (being a bit naughty racing a mk2 rs which I was surprised I actually beat). I fitted rs plug thinking it was spark blowout but still no change. also i dont know if this has anything to do with it but the 2 times it has done it i have been going up hills. Ps the car is at stage 3

Thanks!