Jumping Temp gauge.
Hey all new to site. My wife just got a 96 mustang 5 speed. I noticed we will be driving and the temp gauge acts normal. It doesn't get to hot. But when you put the pedal to the floor the gauge will drop from where it was at all the way to the low side. When you let your foot up it will go right back to where it was. I checked the antifreeze and it is fine. Doesn't have any leaks. The heater does take awhile to heat up, but the ac blows cold. Not sure what to look for.. Have read a few threads that metioned possible head gasket. Could this be the case? I haven"t seen any coolant around. I sometimes do notice a smell that does kind of remind me of antifreeze, but I have never seen it.. Any info would be great .. Thanks..