Change the plugs it might help, as if you don't do hard driving or reguklar long journeys etc it can lead to problems, dont bother with
JCW ones just get NGK irridium range 7 ones (£25 delivereed, whereass
JCW are about £20+ vat each or som,ething equally rediculous!)
I would use nothing less than 97 octane superunleaded. Even my stock
MCS would run like a bag of nails on 95 standard fuel, so a
JCW will be worse. if you can use the 98-100 fuels like BP, sheel etc
It may also be due to your sensors picking up too much heat in the engine intake temps, this can then cause the car to retard itself in an attempt to stop you breaking it by giving it full beans with hot air being used, and so melting something. Thjis is more common on higheer boost cars, but it could be seen in a
JCW
The other factor could be a dicky Tmap sensor, about £30 from BMW and 5 mins to fit.
its difficult to diagnose the problem without reading the fault codes or having a full health check. 1320 (near bedford?) and ThuinkMINI (worcestershire) boith do this service using either a data logger on the road @ thinkMINI or a rolling road @ 1320. I know Thinkmini have a qualified snapon trained and BMW trained diagnostic tech (1320 may also have a specialist).
