Losing power but no codes

[SpiffWilkie]

you would most likely get a secondary o2 code for a clogged cat, but partially clogged would slow air.

I think you have either a fuel restriction, or air restriction. being 10 years? old, i would check the fuel pressure in the rail. do more than just initial pressure, check pressure under load. then replace the fuel filter in the tank. cheap, labor intensive but not difficult.

Question about fuel pressure. The manufacturer specification is 55-62psi. Should it pressurize to that the first time I turn the ignition on? With just turning the ignition to on once, I got around 30 psi. Turning it on and off, it got to 53 psi.

What's the best way to check it under load? Do I need to purge the gauge while someone has their foot on the gas and see if it climbs back to the 55-62psi range?

Edit: Another question about the filter. I know that the filter is technically not user-serviceable. Is it still possible to replace it? I've searched and searched on this site and can't find a thread where someone has done it or explained where to get one.