whenever i drive my lt1 in the city with the heater off, it overheats. But if i drive with the heater blasting the heat gauge does not go into red ( still is high in temp though)

And another weird thing is I would have to have the heater blasting towards the windshield, not towards me or to the feet.
Car does not overheat if I drive on open highway with no traffic. I already replaced the thermostat and that didnt do anything. Someone told me I may have a hole in the radiator. Did any one else have this problem here?

 

I had the same issue on my first 4th gen. Turned out to be a clogged radiator. Have the system flushed first, before you go throwing parts at it. It's a cheap $4 prestone kit from autozone. Set it up and flush away.

Remember to bleed the system afterwards and go from there. Hopefully that's all it is man.

 

Mine did pretty much the same thing, and it turns out my fans weren't turning on at the correct temperatures, if at all. I installed a manual fan switch, and it helped a lot. I then had the PCM repogrammed by pcmforless and i haven't had to touch the swith since then. Whoever had the car before me obviously messed something up.