First time owning a legendary Supra really could use some help.

[Green7mgte]

standard cheap troubleshooting when dealing with temp issues is to replace the thermostat and the rad cap and burp the system. as stated above the fluctuating temp could be a result trapped air pockets.

In the summer time I always use a low temp fail safe thermostat. between 140 or 150 degrees. When and if it fails it just sticks in the opened position so no harm will be had to your engine. Costs a little more but were talking maybe 5 additional dollars.

Yes I know (to low thermostat) can cause issues also, by not running at recommended temp. I disregard this information because I'm a loose cannon and a lightweight masochist.