TPS mV reading

I have a 2001 V11 Sport, and have had an ongoing problem with poor running, and misfires.
Last year I bought a new TPS from Gutzibits, as I was unable to achieve the 150mV baseline setting, with the original one, when trying to set up the throttle bodies.
I managed this when fitting the new one, and setting and balancing the throttles.
When I started it a few weeks back, it would not run or idle well, and I had a job to move it the mile to the new garage.
I thought I’d recheck the settings, and redo them, but when trying to set the TPS, I could not get any reading lower than about 640mV throughout its rotation. The part is almost new, with hardly any wear and tear. Any ideas why the reading would be so high at closed throttle? I have ensured the butterflies are closed. When the original fault appeared last year, I replaced all rubbers also, and the valve clearances, plus new plugs and leads.

May be useful;-