On a 2003 6.0L the ICP sensor is located behind and down below the turbo facing the drivers side. Both the regulator (IPR) and sensor (ICP) are there. The ICP is the furthest back and it should have a silver covered insulator covering it. It may help you to know that the ICP is a three wire connector and the IPR is a two color wire.
my truck when I installed my Quadzilla I mis-plugged the ICP and thought it was plugged in when it wasn;t. Quadzilla box didn;t work and threw a check engine code, so I toke to a buds shop and hooked it up to the OTC Genisys and it showed ICP sensor which on my 04 is located behind the turbocharger. The truck ran and drove fine and it wasn't even plugged in. I am guessing the computer compensates to set values in the ECM coding when a failure like this occurs..............
Well, at least Ford's specs. They get higher than that when you throw the ICP/R system into open loop and set the regulator to 100% DC
The ICP system is the cause of many, many, many surging problems. It still amazes me that another member here (me1mkee) has these exact symptoms, while both Ford and his dealer refuse to replace a 60 dollar sensor. Maybe with the recall out he will get his truck fixed.