I have a 0090 pressure ciruit code lit, had the FPR out and tested buy a local moddifier shop and they say it is fine. 3.4 ohms at switch connectors, popped apart and the plunger is as smooth as new with no restrictions or scoring. Can this still be bad?can anyone check with a new one? I compared it to to used ones, same reading. Is it correct to test this way...of should I just swap it out?

what is the proper way to test (donot have scanner for flow rates) and all roads seem to point twards a ecm problem or a broken line. Tested all wires for continuity, seem fine. can I flash the ecm back to new?

truck info, no tuners bone stock, 62000miles, 2001 dually 2wd, zf-6 manual.
truck is loping, mil light lit, throwing 0088-0089-0090 codes and clack's like a sun-of-a-b!@#