Replaced both thermostat and coolant temperature sensor below thermostat housing. I had to use a 19mm long box end wrench to get at it. Needed also to loosen dog leg for more room. Bled the system for about 15 minutes. There is less fluctuation in the temperature gauge. It hovers around the normal operating mark. When I stop at a red light it might rise about 5-7 degrees but it settles back down when I resume driving. I removed the rad cap and the fluid was right at the top. I might bleed it one more time tomorrow to see if I can get it to not fluctuate at all.
