My 2003 Dakota has developed a intermittent problem over the last month or so. The temperature gauge will climb right to the 'H" after the engine runs long enough for it to come up to temperature and an idiot light comes on and a ding-ding-ding alarm. The first few times it happened I turned on the interior heater and the fan to high and almost immediately the temp gauge dropped fairly quickly back to it's normal operating range. I'm actually stumped as to why the response was so quick as all I was attempting to do was draw some heat off the engine to help cool it. I wasn't expecting the dramatic and immediate response of the engine temp gauge. That still has me scratching my head. Recently it seems that just turning on the heater doesn't have the same effect. Yesterday I pulled over, turned off the engine and turned on the heater etc. again for maybe a minute or two but the temp wasn't dropping. After I started the engine again within a few moments the temp gauge began dropping and pretty quickly was at it's normal operating temp again. I haven't done anything about it because it doesn't happen that frequently and I'm not even driving every day these days. So, my thinking right from the start of this problem is that it's the thermostat. It's probably gotten sticky and worn and isn't opening up when it should some times. Is this an accurate or reasonable assumption. If it is I'll undertake the repair myself. I watched a YT vid and it's a fairly straightforward operation...I have all the tools. So, what do you say...thermostat or could this be indicative of another problem?