Try a new CHT sending unit.
I order it.
Good idea, I can close valve and check how engine works. If overheating disaper it means that maybe vavum selenoid stuck... and my theory was good, but ow is middle of the night here and I will check it tomorrow. If I need to replace SV haven't idea how remove it without disasembly dashboard.If you need to, you can zip tie the hot water valve closed until you get the vacuum issue straightened out.
