Toyota Repair: Overheating Tacoma, temperature gauge, power flush

Question
My 2001 v-6 TACOMA with 155K miles began to overheat when idling after I replaced the timing belt and water heater. Temperature gauge has approached the red zone twice.  I have begun to use the heater to remove engine heat when overheating conditions are imminent.  I replaced the thermostat.  Overheating at idle continues.  Visual inspection of the radiator and hoses did not reveal any obvious defects. My plan is to flush the entire cooling system this weekend (Prestone cooling system cleaner, then power flush via the heater core intake hose) to see if this cures the problem.  Do you recommend any additional actions before I replace the radiator and upper/lower hoses..??

Answer
If it's only overheating at idle and not while driving then I don't see how the radiator could be the problem, could it be that the thermostat even though new is defective? Maybe, yes, I assume the water pump was replaced as well.Go ahead and try flushing it and then let me know the result, I just don't see how replacing the timing belt and water pump could cause this.