1991 Toyota Camry 1991 toyota seems to never warm up

I have a problem that the car while driving and remove your foot from accel while driving the car seems to stall or downshift. The car also never will
warm up above 1/4 on the temp range and heat is only warm. I am disabled and have owned the car for 5 years . Will a stuck thermastat cause these problems?


Thanks

Ncrdisabled