Ok fair enough. Can you not get diagnostics or PP on it? Doesn't have to be a fault light for a fault code to be stored. And PP will obviously show specific readings.
Another thought though, is the EGR stuck open? If it's allowing exhaust in at higher rpm under load it'll lack oxygen and overfuel. I've currently got this issue on the Vec but the effect isn't as bad as yours sounds.
Another thought though, is the EGR stuck open? If it's allowing exhaust in at higher rpm under load it'll lack oxygen and overfuel. I've currently got this issue on the Vec but the effect isn't as bad as yours sounds.