temp guage moves down the faster i go, sometimes bouncing donwards. any ideas?
Possible faulty coolant temp sensor. (If that is what your are referring to)
When you say down, do you mean back to normal or do you mean down to cold.
If it appears to run hot when driving slow, I would be looking at the radiator fan or maybe the water pump.
I’d check the level of coolant in the radiator (when cold), install a new thermostat, and check the connection at the coolant temp sensor. If the gauge continues to jump around after a new thermostat is installed, replace the temp sensor.