It's a 1300+ male which is a good weight for a male, the key with male considering their metabolism is to offer a small rat 55 to 75 grams every 10 to 14 days.
If you feed more they will fast, and at that size he could easily go a year without food.
Additionally he can very well still have breeding on his mind even without the presence of female since he is sexually mature.
On the top of everything else your temps are way off either you keep the animal in the mid 80's with no hot spot or you provide a hot spot and lower temps 78/82 on the cool side and 88/92 on the warm side max.
Oh and thermostat control temps, thermometer read temps.