I have a 98.5 cummins 24 valve and this truck has been a nightmare. I put on a raptor factory pump soon as I fired it up it would miss at idle and the psi would fluctuate from 18 to 25 pounds bouncing around and would drop 10 psi at wot. So put on the airdog2 and worked awesome for a half hour then started the same thing just not as bad pressure set at 15psi and fluctuates from 2 psi. I'm completely lost changed the overflow valve and no fix so my guess is either injector or injection pump. Any thoughts or ideas would be deeply appreciated thanks for your time.

 

What kind of fuel pressure gauge are you using?
1/2" line kit tank to pump?
Take the fuel cap off and try it
It would not be an injector, and sounds more like a pre vp fuel issue. Beware that the vp is not going to like the low pressures

 

Yeah it is 1/2 from tank to injection pump did draw straws as well. My only problem with that is it didnt do this idle **** till the aftermarket lift pumps were put in? and what pressure would you recommend ive heard at least 15psi no more than 22.

 

If the system was not primed correctly you could have damaged the vp
The range I like to see pressures in. (15-20)

 

I had a similar issue on my truck . After blaming the factory lift pump several times I figurd it out. At some point someone adding fuel to the truck broke a plastic fuel can nozzle off and it dropped into the tank. As it broke down little pieces of plastic kept making there way into the inlet if the lift pump. It has a screen there. No prefilter. Check your filters and possibly in your tank for debris. Im running an f650 with the big tanks.