Re: Temp Guage goes up when at a stop only.
I had the same issue. My fan was working, and I had just done a coolant flush. The problem was my radiator. The core was old and bugs and rocks had eaten away at it. I replaced the radiator and BAM. Problem fixed.
Take a look at your core. See if it looks tired.
FYI, the thermostat is designed to fail OPEN, not closed. If your car is over heating while moving, it's probably not the thermostat.