02 taco, 4cy 2.2, 181000 on it. Just did service december so its fresh coolant. The water temp gauge was climbing very high yesterday, would get into the red then drop to 3/4 again. It was 105 outside temp and freeway driving but ive never seen the gauge that high before, it never goes above half usually. No steam at all. Look for radiator blockage? Bad sensor? Maybe it needs a power flush? Any ideas?