[rich weyand]

First question to ask is, How do you know it was running between 210-230?

If it's the dash gauge, then the question is, Which temperature sender is in it?

The temperature senders in these trucks have often been changed out over the years for the wrong ones. Many make the gauge read high, which you may not have noticed in cooler weather -- you thought it was running normal when it was running cool.

First thing to do is use an infrared temp gun to measure the temperature of the radiator inlet when the engine is up to temp and compare it to the gauge reading.

All you might really need is the correct sender unit for $20.