What just happened? Two weeks old: Engine shut down, VSS Error.

[Graderman]

The throttle not returning to idle is most likely an issue with the spring not being seated correctly in the end of the handlebar. I had this happen to me when I installed my cruise control. If they took apart the switch assembly to mess with the TPS, that spring comes loose at the end of the handle bar that returns the throttle to the idle position. The spring popped out of it's hole that retains it and it would act normally, but not fully return to idle, I had to actually "stretch" the spring some so it would properly seat back into position. Once I had it back in the retaining hole, everything was normal.

Throttle function has never been an issue. The throttle position sensor is used to monitor the throttle body valve position, not the physical throttle itself. I don't know what vintage your machine is but these machines are now Ride By Wire there is no direct mechanical connection between the throttle and the throttle body. It's all just electronic signalling.