Head Gasket
The first would be to get something to monitor your engine if you don't already. That can be a monitor like ScanGage or an apt for your smartphone with an OBD adapter. Monitoring your differential between coolant and oil temps warns about the oil cooler efficiency.
You have a 2004, so part of the answer depends on which version of the engine if you have the ICP sensor on the passenger valve cover or not. If you don't, you have a robust EGR cooler and it can stay. If you do, it should be changed to a BPD cooler so you never have to worry about an easy failure of the stock EGR cooler.
Next for me is to make sure you are using a coolant that will not gel, like the OE Gold G05 coolant, although if you are changing it every 30k to 50k miles, it can be OK.
And finally, I prefer not to use any programming modification to enhance power output, although some of the current versions are not as bad as one to two decades ago.
Lastly, proper maintenance of the oil and filters, using only the Ford or Racor branded will hep in longevity.






