[Custom.Chevy]

TRY MOVING YOUR TEMP SENSOR TO THE SIDE OF THE BLOCK. THERE SHOULD BE A PIPE PLUG ON THE DRIVER SIDE OF THE BLOCK. Im pretty sure i did THIS ONCE BECAUSE I WAS GETTING FALSE READINGS. I REALIZE THIS IS NOT THE OPTIMUM PLACEMENT FOR A TEMP SENSOR BUT it may work. Also if your running long tube headers it may be possible the headers are heating up the temp sensor from the outside giving you that high reading you see, then once the thermostat opens and the cooler water flows over the internal part of the sensor its cooling it back down to the normal temp readings. This would explain why the the gauge is reading incorrectly while your laptop reads correctly. It also explains why all your equipment is in working order but not reading like it should be. just a theory. its been so long since i had this issue myself i cant remember if this was the solution but it sounds familiar.