Engine coolant temp fluctuation range

[psxpak]

my 71 el camino temp is shooting back and fowarth pretty drastically, I put a 180 thermostat in and it was shooting up and doen from 180 to 210...like... 210>180>210>180 basicaly as the thermostat opened and closed. i swapped it to a 160 and now its 190>160>190>160. i've never seen a temp gauge go up and down so much all my other rigs just sit at the thermostat temp unless im driving them under a load or on a hot day, this thing is doing this cruzing and idle. when i took the thermostat out it just sat at 125 or so, I took the radiator out and flushed it every wich way today wich didn't make a difference. i noticed the lower radiator hose spring was basicaly only part there in the hose so i replaced the hose, I'm thinking of swapping the water pump next. i'm wondering if maybe theres like spring wrapped around the impeller?? anyone ever had an issue like this?

also, i'm safe posting this here right? i can post a pick of my title it sais chevy pickup lol. I do have a 72c/20 and just sold a 72 k/20 on 37 irocs too