Hey everyone I’m struggling with my Deville trying to overheat. It only does it when it’s under a load. I live in a very mountainous area & when I climb a hill the temperature goes up to the third mark, normally it’s dead center, when I go down the other side it cools back down. The a/c fan comes on but the cooling fan doesn’t. I’ve checked fuses & tested the fan motors everything is good. I should mention that there’s a loss in power also. It barely climbs the hills & mountains but has no problem on a flat road. Help please!!!