Temperature Sensor For Cold Start Valve

I have a 1987 328GTS that I've owned for 30 years. It runs well but has a quirk. I park it in two places. One place is my house basement where the temperature is about 60 degrees in the summer. The other place is in a shared garage area with two other vehicles. In the summertime the shared garage temperature can be near 80 F or even higher if both of the other vehicles were driven the day before. When it is that warm and I try to start it after a few days of not being used, the engine fires then stalls. When this happens I have to crank the engine quite a bit to get it running. Once running, all is well. When the car is parked in the basement for a few days, it starts right up at a higher idle speed that gradually falls back to the normal idle speed. The problem is when the vehicle is parked in a warm area for several days.

I am wondering if my cold start valve is not opening when the temperature is not in the low 60's. Where is the temperature sensor that controls the cold start valve?