Sorry if this is a "douple post" but I must have asked this question in the wrong area earlier. Replaced my 3.4L engine with a Goodwrench engine and all attachements except pulleys were replaced also, including the thermostat. Temperature used to settle at the first hashmark on the guage and, if hot/stuck in traffic, the second fan would start at the second hashmark. Now, the temp will rise to almost the second hashmark before the T-stat opens, drop to the first hashmark, and "wander" between the first hash and halfway to the second. Since the second fan comes on at the same indicated temp as before and when the t-stat opens temp lowers to the same indicated temp as before, I assume the new sensor is OK and the t-stat is the problem. But since there is no indication, except during initial heat up, that the T-stat is sticking - but seems to "wander" - I'm not sure. I figure I'll just replace the T-stat but it looks like a major production just to get at it. Any words of advice? Does it sound like the thermostat or am I on the wrong track? Any advice will be appreciated. Thanks!