HPOP leak? - power/mileage loss + more noise
Have read numerous posts on the HPOP leaks and I'm trying to determine why there seems to be some loss in power, decreased fuel mileage and helluva clattering racket from the engine at certain RPM load ranges. It's an '01 F250 7.3 with 130K miles and starts and runs perfect (other than a perceptible loss in power, economy and increased engine knocking/clattering noise). Its stone stock at this point and I have not tried to pull any codes - may take to dealer for that.
Since some of the possible HPOP leak symptoms similar to mine were mentioned in other posts, is there a definitive way to tell if the HPOP is leaking internally, i.e. by reading the oil pressure to the injectors and comparing to specified parameters? I have no external engine leaks at all and don't really want to do the o-ring change if it is not the cause of the reported symptoms.
Hope someone can provide some straight forward guidance here.