At this point I am covering like 95% of my radiator just to get the temp gauge needle perfectly vertical (operating temp). If I uncover it any more than that the needle will only go 1/4 of the way and if I remove the cardboard completely it runs even colder.

The only thing that will noticeably raise the temp is if I am going 60+mph on the highway, which is pretty ironic since I would think airflow would be very high in the engine bay at that speed..

Could anyone who has had this problem please chime in withe some suggestions on what might be the issue?

 

First thing to check would be thermostat. Possibly stuck in open postion.

 

What vehicle are you working on? What year?

How warm is it outside?

You could have a stuck open thermostat. A stuck open thermostat will let coolant to flow through the radiator immediately and won't let the coolant to warm up to operating temperature.

Which gauge cluster do you have?

Many of these old Toyota coolant temperature gauges like to show about 1/3 to 1/2 the gauge at normal operating temperature, so just keep that in mind.