2005 Dodge Neon temp gauge plz help

Have a 2005 Dodge Neon which has recently when driving
was having some shifting difficulties but I checked
transmission fluid and it seemed low so I add some and it
seems ok now but about a week or two later the car temp
gauge shows I'm over heating however there is no steam
from under the hood or small of coolant and no boiling
noise in fact hood is cool to touch. Now this is while I was
sitting idle at the store so I drove the car and the temp
gauge started going back down to normal so thought it
was fine until I stopped at a light bout 3-4 miles later it
started going back up as if car was over heating so I shut
it off and when light changed started it back up and drive
and once again it went back down again no signs of over
heating going on under the hood However there is steam
coming from inside the car from the top of the dash out of
ac vent near windshield it's like a steamy mist. I need help
plz