I recently had a similar issue with a laptop, though temps wer only up to 70+) where everything looked clean from the outside. It was only when I actually removed the base cover and the internal airflow director (plastic funnel device), that I found the problem - the inner opening of the main exhast port appeared to have a foam filter - this turned out to actually be dust and such causing the airflow to be almost non existent.

Sometimes with laptops you have to physically clean the internals