Rough running

2000 FORD EXPLORER
141,060 MILES • 4.0L • V6 • AUTOMATIC
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JRIGSBY7
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The vehicle loses power when on an incline and struggles to maintain constant rpm's at idle. Runs very rough and chugs (sort of rumbles) when starting and trying to drive almost like choking. Check engine light is on with codes P0171, P0174, P0302, P0303, and P0304. Can anyone give me some guidance?
Jul 23, 2017 at 3:10 AM
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HMAC300
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The first codes are for lean engine which can cause the other three. Check fuel pressure with a gauge it may be low on pressure causing this auto parts rent gauge. See link.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
Jul 23, 2017 at 4:46 AM
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JRIGSBY7
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I have a 4.0 EFI. I see no vacuum line.
Jul 23, 2017 at 6:37 AM
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HMAC300
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some do not have it. Just hook it up like it says and turn on key see what the pressure is should be 35-45 psi no lower.
Jul 23, 2017 at 8:43 AM
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MAXIMILIAM
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We checked the fuel pressure with a gauge,and it was 62-63, above what the link said was normal. We then checked it with engine running and also snapped the throttle, but the pressure number never changed. It was running really rough, and shaking. The exhaust pipe was both blowing and sucking air. Any further thoughts? All is appreciated.

/JRIGSBY7
Jul 24, 2017 at 5:24 PM
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HMAC300
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  • 48,601 POSTS
have you scanned for codes as well? if a misfire it can be a sensor which will need freeze framing so a mechanic can look at the numbers. also try a fuel pressure regulator as the pressure may be a bit high.
Jul 24, 2017 at 10:13 PM
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