On my 96 9c1 5.7 my temp gauge reads below cold, when I turn the key it jumps to hot, but them immidetly returns to below cold, after driving for some time ithe gauge only goes as high as cold or just above cold, never any higher... any suggestions

Sure, when you drive the car, you are getting real time input. When you turn key off, the gauge will go to a no signal mode and not display correct input, hence...odd input. Hope this helps