The IPR is on top of the HPOP right behind and kind of under the back of turbo, most times it is just the screen onit gets clogged or even busted out, you don't have to repace the whole thing if that is the case, they sell just the replacement screen with orings. It is common for them to get clogged after a HPOP has been replaced but if the stock STC fitting was failing it couls have sent junk into the screen.The ICP sensor is the one on the pass side valve cover, that is the injection control pressure sensor, the IPR is Injection pressure regulator.

 

Sorry bud your thinking of the icp