truck is barely running

[2000Superduty7.3]

longer crank than usual, one it starts its seems to be running on 5-6 cylinders, the icp reading is about 530psi. no codes, the buzz test doesnt reveal anything. oil level is good. just replaced the fuel pump, i have a feeling that the fuel pump is picking up air, is this common? anyone have any ideas of what i should look at next? any help would be great. thanks

[7.3'00]

Do you have a good scanner? Normal scanners- such as ones that auto zone uses- do not pick up the codes on these trucks.

And do any rpm's register when it is cranking? What kind of weather are you in? I can name fifty different things, but you'll just be throwing parts blindly if you haven't gotten a good scanner.

If there is no rpms' registering when it is cranking then it may be a CPS. Is it rough idleing? The choppy idleing can be from the cps, ipr, icp, gpr, etc...

[audiocontr]

well you need to work the air out of the fuel line if you swapped the fuel pump. shouldnt take long. Do you know what your fuel pressure is? How many miles? Have you replaced your fuel pressure regulator?

[2000Superduty7.3]

thanks for the feedback, it ended up being the screens in the pickup were so clogged the fuel pump was working so hard to pull fuel through them it was aerating the fuel