Engine Coolant Temp Sensor

[Purplernest]

Hey everyone, ive been having a problem with my engine temp gauge and i think its because i have a bad sensor. The only problem is i cant find the coolant temperature sensor on my Q in order to diagnose it. Can somebody help me locate the sensor? Pics would help.

Just for refference:
-i have a 98 Q45
-The temperature gauge keeps jumping from normal temp to cold when driving fast, my guess is the sensor is loosing ground or its just a bad sensor.

Any opinions are appreciated, thanks!

[3Q Jay]

the sender for the gauge is a single wire (the other one for the ECU has 2).
it is just to the right of the upper radiator cap (follow the aluminum goose neck as it goes back intot he engine).
of course, you won't see it until the plastic cover is removed.