I'm not real familiar with this 3.3 engine yet, but most engines bend valves when the timing belt breaks. So, you don't want to wait for it to break before changing it. Also, BurgPath is correct, change anything that would require the timing belt removal for replacement. Meaning, if the belt needs to come off to replace the water pump, then change the pump when you change the belt. Especially if the belt turns the pump. No use paying the belt replacement labor multiple times. I've changed timing belts, chains and gears on lots of different engines. Sometimes it can be a bear, sometimes easy. Typically you need some special tools. Or at least a good set of tools and an impact wrench is always a plus.