thermostat or gauge?

[whereda40at]

i think i might have a problem with my thermostat or temp gauge. i watch my temp gauge and it takes a while to come up. once it is at the half way mark on my stock temp gauge. when i get on the throtle the gauge will go down. i can do a video of it tomorrow to better explain it. but after it goes down some times it will stay down. some times it will come back up (http://zilvia.net/f/tech-talk/225073-thermostat-question.html#). but never does it go over the half way mark. i had the motor build and it didnt do it until i broke the car in and at about 400 miles is when it started to do it. im not sure if the shop that built my motor had replaced the thermostat. i am wondering if it is a thermostat issue or a wiring with it some where.
how should i trouble shoot this??

[Mr.s13r]

Well im not an expert in this but i might just swap out the thermostat if you know it is old. Also you can check to see if the coolant sensor, the one on the right is good or not. Or just change that too man. Well again im not sure but u can swap those out and see if that works.

[djcobra]

I personally never trusted the temp gauges on our cars, its like an on off switch. Do you have a Power FC with Commander? if so it will show you the water temp on the display, or you can just manually install an aftermarket Gauge tap the sensor on rad hose.

Also check the wire/clip that goes to the 'Thermal Transmiter Temp Sensor' located under the TB, right beside the CTS, it might be corroded. My clip snapped off, had to replace that little piece of shit $24 from Nissan.

Steve.