I have a 1999 Ford F450 Tow truck with a 7.3 turbo .

It loses power and misses when I give it gas but when driving normal speed no problems.

I had a ford technician look at problem with a computer and he said number 8 injector . Today number 8 was changed.

Test drove it same problem. I also
changed th fuel filter.

And I emptied the tank to make sure No water

 

I am still a newb here myself but I'll start off first. Welcome!
Did they/you check the fuel filter?

 

I changed th fuel filter. And I emptied the tank to make sure No water

 

Check for boost leaks and exhaust leaks.
Do you have any WOT runs on a system that can record them?

 

Sorry to see the tech is a newbie and replaced the #8. That is a rookie mistake on his end. Sure hope you don't let them charge you for that!