ok is it cutting the power liek a boost limit cut, if so test the altanator with the lights on at 3k rpm, the power should be over 12v, if its lower like mine was the alts not giving the bat the charge and so the ecu is cutting it till it recives it

trust me as i keft mine cause when i drive gentle its fine, but on the way back fro central day the batt was totally dead ( mind was racing on te A407 for a few miles ay a steady pace, me pother mate melted his piston and done his headgasket there too