okay this has been an ongoing problem for a while now. ive checked everything. (literally) replaced the temp sensor, the coolant temp sensor, the fan switch, the thermostat, flushed the radiatior, and everything runs well. however, my temp gauge on my dash tells a different story, at idle it climbs to where it should, right near the middle. and until i hit 40mph tells the truth. once i go above 40 though, thats when all hell breaks loose. the temp needle climbs WAY past H and will fluctuate at its own desgression. untill i slow to about 35 when it drops back into the proper range. what the hell? i know its telling me lies because if it truely was that hot, id be boiling over as well as already warped my head. could it be the cluster itself? im aware that there was some band aid type work done to it in the past, since when i got it, i found a "vampire" tap being used to ground out the fan switch so that the fan was at constant on because the previous owner was too cheap to spend the 25 bucks to replace the fan switch. so, does anyone have any ideas as to what could be left to be the cause of an incorrrect temp reading? the only other thing thats "wrong" is that i dont have my secondary o2 sensor hooked up becasue i cant get an extra bung welded in. could it be that my cars running lean due to the improper o2 readings? im out of ideas... thanks guys.