I have been having a high cold start up RPM issue (1800 rpms) with my 5.4L after doing TB re-learns, and based on research here and advice from others, I decided to try a PCM re-flash. Took My 2005 Super Crew to a Ford dealer the other day to have my PCM re flashed. They said they always do a diagnostic before they do a re-flash. They performed a diagnostic, but refused to re-flash my PCM saying it is too risky. Is it really? $250 gone with no resolution.

 

I would not say "risky"
But
You cannot go back
Meaning
Once you reprogram one, you can't ever have the original program back
We used to re program them to get rid of a certain trans shifting error
Then the people would sometimes come back complaining of something it was doing "now" they didn't like
They would ask for their old program back and it was "never going to happen"