My temp gauge doesn't work right. Sometimes I can get in it in the morning first thing turn the key on and it pegs out at hot. Then it will fall all the way to cold then back to hot. I have replaced the temp sending unit but did no good. Any suggestions or help thanks

 

Unfortunately, 02 and later have an electronic Gauge Cluster. That being said, there is a possibility a loose wire at the sending unit or possibly a chafed wire.