2000 toyota tacoma

my 2000 toyota tacoma for the first time yesyerday got really hot or at least the temp indicated that is was everything looks ok under the hood but going up a hill it showed that it was hot it goes up and down do you think my thermostat and temp switch should be first to change???

 

my truck just started to show over heating on dash only everything under the hood looks ok should I just change the temp swtich and thermostat???

 

The thermostat might be needing a replacement. I would start there, its easy and cheap. If this does not resolve the issue, then I would go into the switch. G/L!