So, I haven't found a fix on here yet...

2000 3.2 TL, Just replaced the thermostat and put in new coolant. Switched relays with my horn relay, horn works so it wasn't the relay. Replaced the fuse with a new 20A with indicator light, the fuse is still good. One fans wiring was bad so I have the fans wired together. Last night the fans worked, today the car was overheating again. Blasted the heat to keep it in the middle of the temp gauge. Any fixes or suggestions or similar issues?

 

I recently did very similar work to my car as you... my temp gauge would only rise when the car sat still idling. i bled it with the radiator cap off
for what i thought was long enough. well i took it up to my shop and they bled it with a funnel for 20 mins or so and fixed it...
supposedly a bubble was caught around the sensor in the radiator and it wouldn't send the signal to the fans to kick on to cool it down...
a bit embarrassing but the car runs fine now... maybe that'll help you...

 

Ok, so possibly getting a wrench in there and crashing the seal so my antifreeze touches the sensor may work... What I did for right now is I hooked up the fan to a 12V DV piece and ran the wire into my power outlet under the radio with a 20A fuse as a temporary fix. Works out because, as we all know, that power outlet doesn't keep power flowing when the car isn't in accessory or running. Just my temp fix for today