My Onan Generator is currently shutting down after running for a short time. I have had problems with this generator in our 2000 American Eagle since we purchased it in 2017. I had 210 hrs when we purchased it in 2017 and now 325 hrs. I had a very qualified technician check it out and replaced the control panel in 2017. I turn it on several times a year, load it up and it has been working most of the time. It seems to shut down when I need it. The code was 33 coolant high temp. I have changed thermostat, radiator cap, sensor, fuel filter, air filter. it is still shutting down with code 1 high temp. Any suggestions?