Been a while, but I think the problem is fixed.
Thanks to unfazed who mention that the TPS can go off, well on checking mine it was completely wanked., the readings both for the static test were higher that should be, and the test when you twist the throttle we’re all over the space, jumping from anything from 3 to 18 k ohms.
So looked for a TPS on eBay but nothing apart from one in Germany £120 plus postage, unknown make, so I bit the bullet and got an OEM one from Fowler’s £150 delivered.
All fitted and have had a couple of rides now, the tacho is behaving itself, but the biggest difference is that the bike, now at nearly 90,000 miles feels like a new bike, the throttle pickup is so smooth, guess the TPS has been on the way out for sometime.
Thanks for the advice,
Don.