What works for me is to torque them cold, run the truck, torque them hot, and repeat in a few days. They're not going to grip deep enough into the threads to "lock" in the heads until they heads are expanded from heat and then contract as they cool. You can think you have them tight enough (when cold) that they will break if you wrench on them any more, but when everything is hot you can easily get another 1/4 or 1/2 turn on each bolt. That's when they're right.