If it sits too long on the throttle body, it might damage the coating
in the throat of the throttle. That won't really *harm* the throttle body,
but it will bare the metal, which will oxidize as well as build up grime
a lot faster.
That's not saying it *will*, but then, a lot of the sensors on these trucks
have plastic bodies/housings.
A friend of mine got some carb cleaner on his throttle position sensor
while cleaning his throttle body housing, and didn't notice. A week later,
he had to replace it and the plug, because it melted and shorted out.
That plus my melted screwdriver handles convinced me to use the stuff
that was supposedly safe.
Cheers-
Chris