'92 Tempo overheating

That was my wife writing. I believe that my engine overheat condition is caused by my fan. I have replaced my fan motor, thermostat, water pump, and radiator. My engine overheats when I am sitting in traffic.
In no traffic, on the highway, the temperature gauge reads alittle higher than I want, but the needle stays out of the red zone.
What I need to know is if there is a temperature sending unit or something to cycle the fan motor or what?

Also, I have a code 23 or 123. I have a "Service Engine Soon" light. And a code beeper thing beeped out 1.2.3. I THINK that is the throttle position sensor and my rpm is going crazy. The idle is too high.

I tried the throttle position sensor from my Ford Explorer V6, but this made no difference.
How do I test my throttle position sensor to see if it is any good?

AC does work. When the engine runs hot, the AC compressor blows refrigerant from the safety valve. Now, that right there is a good indication that the fan is not cycling properly. The AC needs the fan to keep the head pressure down. If the head pressure rises too much, the safety valve on the compressor will blow.
I have seen the fan work, but it doesn't come on until the engine is already way too hot.
I have rigged a light switch in the cab to manually turn the engine fan on and off. When the car is in motion, I have no problems, but, when I'm sitting in traffic, it runs hot. So, I turn the fan on with my switch and the temperature goes back down.
But now, what am I going to do about my throttle position sensor? My rpm goes way too high at idle and pulling off from a red light, the car can go up to 40 miles per hour all by itself without me touching the gas.