High Idle when hot - low power on up hill

[fixkick]

its over $200 device. (motivates me big time)
those nipples come off, (screws ) but is risky if the seals inside are wrecked (oh so easy)
try vinegar soaks, (its an acid)
finer stiffer wire (piano strings, guitar strings)
concrete etch (phosphoric acid) and brick etch,. home depot.

whats there red rust, or calcium (chock like) ? my guess, chock
but if last guy, put in a new mix of old green antifreeze and new. it turns to Gell this Gell, bakes to glue then like tar.
lots of ways to mess up coolant.... for sure lack of flushes.