Q: 1994 k1500 5.7l replaced 195 deg thermostat then a month later temp guage rises to 210 degrees at stop light then goes back down a

flush & filled radiator and replaced 195 degree thermostat about 700 miles ago and now temp gauge rises to 210 degrees whenever coming to a stop then goes down to 160 deg when pulling out and back to 195 deg until stopping. Also heat isnt good inside cab when turning it on

My car has 194000 miles.
My car has an automatic transmission.