Temp gauge broken...moves str8 to H

[redciv1]

I realized after my swap that my temp gauge was not working properly. From the minute you turn the key the gauge goes to H. So from overnight to in the morning starting the car the gauge moves to H within 1-3 minutes. So this is what I have done so far.
-I took the plug off of the temp sensor and the gauge fell to C.
-Then I put the plug back on the temp sensor and it went up to H.
-I bought another temps sensor and unplug the harness on the one on the motor and just plugged the new sensor in while holding...nothing happened.
-Then I touched the new sensor that I was holding to a piece of metal on the block and the gauge moved up to H as normal.
I wonder is it the gauge cluster itself because...
1. Fuel gauge does not work either it is stuck at F and every now and then drops down to the correct level and then rises back up to F.
2. Previous owner had Indiglo gauges and it looks like the put glue or something on the temp gauge area, so I am wondering if they disturbed the gauges. Tempted to get an aftermarket temp gauge and mount on A-Pillar. What is involved with installing aftermarket Electrical Temp Gauge?

[TEG90]

it sounds to me like a wire is pinched on body thats why it moves to H when u touch the sensor to body. either follow th wire thru wire harness to c if it has break or crack in coating on wire or take out cluster and c if wires are touching or pinched or touching metal. hope this helps.

[redciv1]

Thanks. That temp wire heads straight into the temp gauge? I will try to trace down.

[TEG90]

yeh my fuel gauge did that b4 and its cuase one liittle wir under my back seat was pinched and touch metal.