The STPS can also fail, but it can't kill the engine.
So if you're getting the classic symptoms of stalling randomly, especially after a highway stint, and shutting down, working the throttle, and re-starting solves it temporarily... it's the TPS.
The STPS's effects, whether it fails or is working are fairly subtle; I replaced mine long after the TPS replacement, mostly out of curiosity. I scored a new one someone had ordered by mistake (they meant to order the TPS) and after installation and calibration, the bike was immediately a little more tractable in low to midrange throttle settings.
That said, many people disable the secondary throttle system entirely by removing the secondary throttle plates. This removes the throttle restriction in fifth and sixth gear and also gives more abrupt throttle response down low, which some folks prefer.
My preference is better fine control down low, for earlier and better-controlled corner exits. My Vee came to me with secondary throttle plates removed and discarded, so I bought a set of throttle plates from another Stromtrooper and was pleased with the result.