89-93 Dodge Cummins diesel loss of power?

About 100 miles into a trip the power drops off and it will only run 45 MPH even at full throttle. It doesn't die and runs that way until I get home (20 to 40 miles). After it sits over night it starts and runs as normal. Could it be a Clogged exhaust, fuel filter?

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  • J J
    Lv 7
    8 years ago
    Favorite Answer

    I think you should do a fuel pressure test, sounds like the lift pump stops working. I've seen some Cummings run without the pump working so I'm going in that direction. If it were the fuel filter it wouldn't be any better in the morning. Nor would the exhaust unclog it's self.

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