Engine runs hot on highway with speeds greater than 45 mph?
 

My engine runs very cool around 45 or below mph. When I am on the highway around 60-70 mph the car will go from 1/4 temp up to 3/4s in a matter of 5 -10 mins. Any ideas on what it could be? I did hear some slight pinging going up a hill around 60 or so. Do you think at this mph it could be to advanced? I have it set to around 14 ATDC. What about cooler plugs? Thanks.

You sure you don't mean 14 Degree before t.d.c??

Check the simple things first.

Coolant level/mixture. Leaks, thermostat, fan/clutch, etc.

You running A/C? any mods? 4.11 gears?

I do not know if it is the raidiator but if it is you can buy a 4 core one at auto zone for just $130.00

Make sure your black "curb scraper" is still installed underneath your front bumper. Believe it or not, that little piece makes a big difference in cooling.

What does the crub spacer look like. I might not have one in my car. Not sure. Thanks.

It looks like a black "air dam" that attaches to the bottom on the front bumper (this is on an LX, I am not sure about a GT). It is just made out of plastic, pretty hard to miss if it is there. Good luck!

Yes I have that on my car. I thought that is what you meant. Would pre ignition cause this too?