temperature gauge
 

chevy tahoe, wind chill in minnesota is about -20 degrees.
check engine soon light came on after wife got off interstate, "8 mile drive to work" temperature gauge start's going up and down on the interstate. I changed thermostat and made sure all fluids were fine, temerature gauge still going back and forth, friend say's computer very sensitive give it a couple day's what should I do

Well, this is a Mercedes forum, but you should pull the stored fault codes and see what they say.