Okay I got a 1998 toyota camry 4C and I just got a new Temperature Gauge Sending Unit at auto zone and I install it and I get going down the road and the cool/hot gauge goes right near hot so I went back to auto zone and got another one and it does the same thing. The old one it never done this unless i'm running the motor hard then just stop for a few mins then it goes up but never over the middle. and when I open the hood the rad hose are norm temp I can hold my hand on the hose for more than 1 min and the coolant reservoir is norm it's not pushing the water back plus I just redone the coolant with red toyota.....
I'm lost

and I don't feel safe with it like this...I'm making my way back to Texas from WA and I don't need it over heating

Please help