Where did you install the sensor for your new Gauge? I had a whole bunch of problems with overheating when I first got my M/H. After many mods it settled down to 210 F on a flat. The fan clutch never comes on in normal driving only when climbing long steep hills will it come on. I thought 210 was too high also and went to a 180 f thermostat which lowered it to 195. It ran fine until the outside temps dropped in the fall and winter, I would get eng codes. I shot the sensor in the head with my IR gun and compared it to the thermostat housing. I found a 15 degree lower temp in the housing than what my gauge was reading. I re installed the 195 thermostat and no more eng codes. I said all this to say that gauges can be off and where you install the sensor can make a difference.