I have a 2003 Mitsubishi Galant with a 4g63 SOHC 2.0l engine. I have noticed that when at highway speeds the heat gauge drops almost close to C indicator and if I accelerate hard I get a burning smell from the air vents. I see no reduction in oil or coolant. Also the engine runs at optimum temperature at normal city driving and no burning smells.
What can cause such a behavior? I have read that a stuck open thermostat would behave the same way as well. But is this true? Also, I have closed 3 leaking cores in my radiator if that has any effect on this. I have scheduled a test run with Mitsubishi, but that's in a few weeks and am afraid if the issue is a critical one to drive around.
Any idea on this is very much appreciated.