Focus st3 facelift

Description:

Only just acquired this, it’s a tidy car with plenty of of mods but it’s started misfiring, at the moment I’ve done a sniff test and it passed that, I’ve changed the plugs but it’s made no difference, it doesn’t overheat either, the car itself still drives with loads of power in every gear just seems to misfire on idle, previous owner recons it’s around 290bhp but there’s no proof loads of mods which include lowering springs
Stage one remap
Updated brakes
Sports exhaust
Ecu holder
Silicon hoses
Uprated plenum
Bigger intercooler and probably more I’ve forgotten,
I’m really gutted to be passing it on but I just can’t afford to look into it further, I need another car quick before the 24th, this still runs and drives and will probably last a while, I driven it 340 miles a couple of weeks ago with no issues so might not be anything too serious, the engine itself sound nice with no knocking etc, and I’ve also just put a fresh mot on this too