In this case I don't think the fuel pump is an issue but could be. We found running pressure was usually not an issue BUT dead head pressure was. Causing sluggish performance on high demand and hard starting hot due to vapor lock. Connect a known accurate fuel pressure gauge at the fuel filter. Allow vehicle to reach operating temperature. While watching fuel pressure temporary clamp off return line and you should see a spike of about 18 PSI or soCheck your fuel pressure too. Those are notorious for low pressure causing issues. 9-13 is spec, but anything under 11 and it'll be hot garbage. You want to be at the high end of spec for it to really run good. This means you'll have to buy a new inlet fitting. I got mine from RV Morse Marine eons ago but sadly dude kicked the bucket a few years back. One time I had a plugged fuel filter and another the spring in my regulator had broken. I think at one time I had a stock type regulator that was adjustable but it maxxed out at 11 or so psi.
No. No CEL either.Might be time to revisit the throttle body and make sure all the screws and bolts are tight and no air is getting by any of the gaskets or seals. it could be a loose screw or maybe a warped or nicked gasket surface that is allowing air to get sucked in when you whack the throttle lever. Apart from the code you mentioned, has the diagnostic reader shown or thrown any others??
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