I have a 91 ls 400 thats running hot i check everything the radiator was cracked so i replaced that and it is steel running hot help

welcome, use this site www.lexls.com to do a coolant flush. also try searching.

When you say running hot, what do you mean? Where does the temperature gauge primarily when the car is warm? Have you changed the thermostat and the radiator cap as well (on the reservoir)?

+1 on the thermostat. had the same problem with my sc4

+2 on radiator cap and thermostat...