OK, let me be more precise. The engine starts cutting out at exactly 4,000 rpm, no more no less.

That makes me think something is set to trigger a fuel cutoff at that point, otherwise the problem would manifest itself in a less precise manner.

On that basis, I am confident it is not a mechanical problem, more likely to be an electrical one.

So, can anyone shed light on the rev limiter system that has been put in place to protect the engine from over revving in park or neutral?

thanks