Small Block & Big Block Chevy Specific - Cooling Problems

I have a 96 WS6 and when it is running the engine heats up normally at first but then it takes off and escalates very quickly. The fans are running because I can hear them. Has anyone else had this problem before? Could someone point me in a general direction?

is it overheating in town or on the freeway?

in town

Is your coolant old or low? Nasty color? My driver just did that, just replaced the coolant and made sure it was full with no air locks and it cools just fine. I would start there first.

My coolant level is fine. New I will double check on the air locks

Ive read that one way to remove those vapor locks is to drill to small holes in the rim of the thermostat. It wont effect the cooling any but will prevent the air from being trapped.