I bought my '91 Carat with a hot running condition.  It would run right at the top of the LED or a bit above.
I did 2 things:

1   Flushed the cooling system, especially the radiator.  That brought it down noticeably.  Replaced antifreeze with phosphate-free
2   Changed to synthetic oil, Mobil 1 15-50.
That made a BIG difference.

Now it runs consistently just below the LED, in a high ambient area, central SC  "hotter than hades".
No other changes were made to engine whatsoever.

cheers,
Steve Cotsford
Columbia SC