If it cools ok in the shop, is the hood up? That matters in my experience.
If everything is the same sans the ambient conditions (inside a relatively cool shop vs out in the heat), it still feels like a lack of fan. Why this is showing up now (and if it's a fan issue or something else that is finally overloading the system) is up in the air though.
FWIW, most performance stats (like Mr G's) start opening about 10*F below their rated temp. So yours sounds good.
If everything is the same sans the ambient conditions (inside a relatively cool shop vs out in the heat), it still feels like a lack of fan. Why this is showing up now (and if it's a fan issue or something else that is finally overloading the system) is up in the air though.
FWIW, most performance stats (like Mr G's) start opening about 10*F below their rated temp. So yours sounds good.