My TPS wore out, Graham.
The symptoms were that I'd be riding along at usual motorway pace and there'd be this hesitation almost like it was running out of petrol, but not quite. It drove me nuts for a couple of weeks as I tried to work out what was wrong. It didn't show up on acceleration or cruising at 50mph, just 80mph which is my usual cruising pace.
Eventually, I bought a multimeter and you could see the voltage drop as the throttle went over what was presumably the worn out part of the trace that corresponded to around 5500rpm or 80 in top. It was quite easy to do the check, so grab your multimeter and crack open the service manual.
Having said all that, my bike is very high mileage. I think it went around 120k miles.
Top tip, the Yamaha T-Max TPS sensor is the same as the Fazer 1000. And it's a lot cheaper to get a second hand set of T-Max carbs than Fazer carbs.