New fuel pump still runs like crap

[rangerboy1986]

I have a 86 ranger. 2.3L 5 speed 4WD. I have 2 fuel pumps, one in the tank and one on the frame rail. It spits and sputters under load and when driving it at higher RPMs. However if you push the clutch in and rev it up it runs great with no issues.
I unhooked the fuel pump on the frame rail and it wouldnt start, that led me to believe the pump in the tank was completely wore out and wasnt working at all. So i replaced the fuel sending unit, and pump in the tank. cost me $115.
It ran better at first, some sputtering at higher RPMs when driving but not nearly as bad as before. After driving it a few miles it seemed to get worse, like it was before i changed the sending unit and pump.
The screen on the old pump was pretty clean looking, my gas tank was really clean inside to be 28 years old.. I dont think it could be a fuel filter since the screen in the tank would catch most of the stuff.
Could it be the inline fuel pump on the frame rail? I read online that the in tank pump is low pressure and the inline pump is high pressure. Maybe that would explain why it runs rough at higher RPMs.?
Has anyone experienced this and what fixed it for you? ignition, crank position sensor, new fuel pump???

 

[swynx]

not sure if your 2.3 has one, but my 4.0 used to do the same thing, i replaced the pump it got better, except at high rpms, it would die after a high rpm run. i pulled the fuel pressure regulator and it was all gunked up with some black tar. replaced it and havent had a problem since.

you might test the fuel pressure also.

 

[94RoadkillRanger]

The fuel filter is cheap enough to replace without testing it. My 1999 Escort had it's fuel filter replaced once, three years in a row, fixing the problem each time.