Hello - Looking for opinions......I purchased this car new and it always warmed up quick. Last winter that changed and it now will not reach full operating temp when driving and when it idles to operating temp I can control the engine temp gauge (dummy) by turning the climate control up. This threw a P0128 code so I suspected the T stat. Installed a new one and it operates the same so I installed a new ECT sensor, no change. I did take out the new tstat and put both new and old in water and they both opened at ~ 182F and fully open by 190F.
I am at a loss about this as I cant see where there is a bypass I am missing. I did block the entire rad with foam board and its much better but even after 30 min on highway its only 1/2 way on the gauge and will drop when I crank the climate control.
The deal said they never heard of this and I have wrenched on cars my whole life and I am getting frustrated and im getting 18-20mpg currently.
Any help would be greatly appreciated.