2007 F150. Been having some issues with the temperature mixer for a while. Sometimes works properly, other times it’s all over the place. Y’all are going to think I’m crazy, but the temperature jumps all over the place when I hit a big bump. I can hit a bump or jam the brakes and it gets much hotter coming out of the vents. I then have to make adjustments to get it right again. Water level in the radiator is good. No other issues besides the mixer. Anyone ever changed the mixer? Easy job?