I replaced the thermostat on my Trailblazer after a P0128 code. It fixed the problem for about a week. After spending 5 hours replacing that thing, I am now in the same situation. With one exception, all the other gauges are going crazy on me. My battery gauge is fluctuating, along with the temp and oil gauge. What should I do now? I am doing all this on my own and could really use some advise.