Anyone know where i can get an adjustable fuel pressure regulator for a 99-04 F150 5.4L triton fuel rail?

 

The 99 fuel rail doesn't have a removable fuel pressure regulator. A 97-98 F-150 does. You will need one to install an after market regulator on the fuel rail. Here is a link to a write-up for a Mustang. Yours will be similar.
http://neptune.spacebears.com/cars/stories/fuelreg.html

Regards

Jean Marc Chartier

PS. NO, a Mustang rail won't work.

 

Not on a mustang, This is a 1995 Thunderbird with a 99 Cobra DOHC but they used 99-04 F150 fuel rails....So I was trying to find a regulator to adjust the fuel & dial it in a little better, just trying to find a model that works.