Dude, you're way overdue for timing belt and water pump replacement, they're to be replaced at 96,000 Km or 50,000 miles For V6 or not. as for the idler pulley, it's up to you to change it or not but this is a good time to replace it because you don't have to pay for labor(labor covers timing belt, water pump, and pulley), you just pay for the part. It will cost you more if you later decide to have it changed(part+labor).