The throttle position sensor was a recall item on some bikes.
Go to the Aprilia website and lookup for recalls. It is more likely than not that it has been done. The faulty TPS has a certain number but so far I can't find the thread where this is stated.
While the TPS is beginning to die, you will have a very jerky ride with poor throttle response and lots of stalling. once it has died you won't get the bike started. Here is a sorry tale and how it was eventually fixed
https://www.apriliaforum.com/forums/showthread.php?332241-low-revs-misfire/page5&highlight=tps
A lot of bikes use this TPS Yamaha XJRs are an example but the TPS will be astro from Yamaha also.
Probably the cheapest is for the Hysong GT650. When last seen it was £48 and is exactly the same part manufactured by the same company.
https://www.apriliaforum.com/forums/showthread.php?343046-TPS-trail&highlight=tps