Need some help on this cooling issue

[Bryce'sStang]

To start off I just got done replacing headgaskets, cam and timing chain and I am still having the same problems I had before. The car will run great at idle and run a long time with out getting hot. Then all of sudden both temp gauges sky rocket. I come to an idle and it will cool down. here are some things I have done.
1. Changed thermostat twice
2. Changed ect.
3. Fan does come on high
4. New Stewart water pump
5. Compression test are all around 145-150
6. Two radiator caps
7. Flushed cooling system
8. Burped system several different times
I know I need a bigger radiator but it has only been 30-50 degree here so I would think it would be fine. Another thing is I know the temp guages are working (stock and aftermarket) But the engine does now feel to be how and the radiator is cold to the touch!!!

 

[sldghmr]

Could it be the actuall temp sender itself? Not the ECT, but the little one at the front of the intake. Seems like you change EVERYTHING else.

 

[Badlilstang]

You verified the timing was correct right? Strange problem.. id be posting this in the stewart component forum... they have helped me in the past with my cooling issues. Thermostat was installed with proper flow direction right? I would like to know what you find when you fix it.

 

[Bryce'sStang]

Both the stock guage and my autometer guage do it!!!!