5.9 12v w/ Auto transmission No top end, just dies

[Fireball 13]

Replaced fuel filter, changed oil, topped transmission fluid, replaced 94-98 Dodge 5.9L 12V Cummins Fuel Pre-heater/Strainer. Good power in lower end, doesn't like hills. HELP
Its get up and go, got up and went. Bogs down to 35 mph, finally gets to the top, the runs like a regular workhorse.

 

[Bob4x4]

You need to test fuel pressure,boost to start

 

[fest3er]

How much fuel is in the tank? Does it lose power when the tank is full and when the tank is near empty? It's possible that the float at the bottom of the fuel basket in the tank doesn't work. Fuel is drawn from the basket. It's supposed to open when there's enough fuel in the tank; this allow the basket to fill. But on hills when the fuel level is low-ish, the fuel flows to the front of back of the tank, letting the float drop and close; this retains fuel in the basket.

If the truck runs well on the level but 'fails' on hills, I might suspect the float is not closing.

 

[Fireball 13]

Tank is full.

 

[Fireball 13]

Will test, thanks

 

[AndrzejConner]

That's a classic symptom that your idle is set too low. The adjustment is a 10mm bolt with a 10mm jamb nut on the rear left side of the injection pump. Follow the throttle linkage down to it. I'm thinking you want to be at or near 800-850rpm in drive with your AC on. Yours may need more or less. Try that before going into the tank.