spongeBOB83

in the workshop in neutral it like a rev limiter cuts in at about 4000 rpm but driving the car its more like a spped limiter

our customer said it fist started cutting out at about 120kph but now says arount 80-90 kph I don't think it would be the coils becuse the misfire would be there all the time it almost seems like some kind of governor cutting in could it be a faulty boost control valve?

I have a customer who has an xr6 turbo and he says that when it gets to a certain speed it feels like a limiter kicks in but only really when he puts the pedal flat to the floor I have tried to clean and lube the boost solenoid but it hasn't seemed to make much difference is it possible a fuel pump not supplying enough fuel when the engine really needs it?